Among the first to write about viral marketing on the Internet was the media critic Doug Rushkoff.[16] The assumption is that if such an advertisement reaches a "susceptible" user, that user becomes "infected" (i.e., accepts the idea) and shares the idea with others "infecting them", in the viral analogy's terms. As long as each infected user shares the idea with more than one susceptible user on average (i.e., the basic reproductive rate is greater than one—the standard in epidemiology for qualifying something as an epidemic), the number of infected users grows according to an exponential curve. Of course, the marketing campaign may be successful even if the message spreads more slowly, if this user-to-user sharing is sustained by other forms of marketing communications, such as public relations or advertising.[citation needed]
Exploits common motivations and behaviors. Clever viral marketing plans take advantage of common human motivations. What proliferated “Netscape Now” buttons in the early days of the web? The desire to be cool. Greed drives people. So does the hunger to be popular, loved, and understood. The resulting urge to communicate produces millions of websites and billions of email messages. Design a marketing strategy that builds on common motivations and behaviors for its transmission, and you have a winner.

If you have decent writing skills you can start a retainer writer business. Mastering your pitch will put you in a position where you can land awesome writing gigs. You can then complete the work yourself as you establish yourself in this space, and from there, the sky is the limit. Outsourcing is key to creating a passive income stream from this idea.
​Self Publishing is mainstream today. When you purchase an eBook off of Amazon there’s a pretty good chance you’re buying a self-published book. Self-publishing is also ridiculously easy. I tried this a few years ago and couldn’t believe how simple the process was. To self-publish a book you’ll first need to write and edit it, create a cover, and then upload to a program such as Amazon’s Kindle Direct Publishing. Don’t expect instant success though. There will need to be a lot of upfront marketing before you can turn this into a passive income stream.
In order to build an audience, you need to have a platform. You need to have something worth following and sharing; something that’s valuable to others. And that, of course, takes time. That’s not to say you can’t build a huge audience in a short amount of time. But as much as we hear about the people who’ve succeeding at doing this, we don’t hear about the millions of others who are struggling every day to get just a few more fans and followers.
Determine who your target audience is in the earliest stages of your campaign creation. To achieve this, ask questions such as: Who do I want to connect with? What content would they feel passionate about? What are their hopes, dreams, and values? Why would they care about my campaign? What will can I do to make them want to share my content with their social network?
The use of Viral Marketing is relatively simple. It’s about the fact that people pick up and pass on the marketing message on the internet and social media. That’s why it’s important to first come up with a marketing campaign that’s not just inspirational, but also easy to share via for instance Facebook, Twitter, YouTube or LinkedIn. The marketing message needs to grab people’s attention and generate interest right away. It’s also a good idea to choose a specific target group that is almost certain to pass the message on in their network. That’s why it’s wise to choose a marketing message that’s easy to share with friends, fans or followers. That way, the message can spread across the internet like an oil spill, and even influence other groups via the target group.
You brought some awesome examples. One of the best ways to get your campaign off the ground is by starting with the ideal audience. I find that I can use data to find my top customers and then make those into ambassadors, nurture those relationships, to create an epic viral campaign. Gilles de Clerck, founder of the Growth Revolution, talks about it here -
I've now only got an SF rental condo and a Lake Tahoe vacation rental in my real-estate-rental portfolio. Although I miss my old house, I certainly don't miss paying $23,000 a year in property taxes and another mortgage, and dealing with leaks and managing terrible tenants. I drove by the other day and couldn't believe how much noisier and busier the street was than where I currently live. I wouldn't be comfortable raising my son there.
1. The batting cage idea is very risky. I’ve seen many of them close over the years and it is not anything close to passive income if you want to keep the business going. You have to continually promote it and target youth leagues, coaches, schools etc to catch all of the new players who grow up and want to play. I’ve played at probably 8 batting cages over the years and 7 of them closed.
What I did: I first identified my favorite places in the world to live: San Francisco, Honolulu, Paris, Amsterdam, New York City, and Lake Tahoe. I then looked up the median rent and housing prices for each city. Then I factored in private education costs for two kids to be conservative given I may not have two kids and public schools are often good enough. After calculating all vital costs, I then did a self-assessment of how happy I was making $50,000, $100,000, $150,000, $200,000, $250,000, $350,000, $500,000, and $750,000. I decided working 20 hours a week making $200,000 a year is the best income balance for maximum happiness. 
This is mostly passive once you have it all set up, but it does take a lot of work at the beginning. Real estate investing also requires occasional maintenance. Currently, we invest in a couple of rental properties and earn about $500 profit from each per month. You can read more about my rental properties at How and Why I Became a Landlord.
The ALS Ice Bucket Challenge started in 2014, which was an online effort to raise awareness for people with Amyotrophic Lateral Sclerosis (ALS) disease and to raise funds. The campaign was able to raise $115 million in a span of just eight weeks! The challenge for people was to pour a bucket of ice-cold water over their head and challenge minimum three people to do the same and make a donation to The ALS Association.

To save time and effort, a person can group two or more of their passive activities into one larger activity, provided they form an "appropriate economic unit." When a taxpayer does this, instead of having to provide material participation in multiple activities, they only have to provide it for the activity as a whole. In addition, if a person includes multiple activities into one group and has to dispose of one of those activities, they’ve only done away with part of a larger activity as opposed to all of a smaller one. 

A few months later after the ad was launched, the ad agency Wieden + Kennedy made a series of more than 200 short ads featuring Isaiah Mustafa, responding to comments and questions posted on social media platforms like Twitter and Facebook. The campaign resulted in an increase in Twitter followers by more than 1,000 percent an over 6 hundred thousand people on Facebook liked the ads!
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While stocks are terrific income producers, they can be volatile. Every few years, the stock market tends to stagnate or drop for a while before recovering, and that can be problematic if you were counting on your stocks having a certain value at a certain time. One way to lock in an income stream is by buying a fixed annuity (as opposed to variable or indexed annuities, which can have steep fees and overly restrictive terms). Annuity contracts will be more generous when interest rates are higher, but here's how much income they might deliver at recent rates:
M1 Finance: M1 Finance allows you to modify your investment selections whenever you’d like, giving you the freedom to play a bigger role as an investor. At the same time, M1 does the work of balancing your investments for maximum returns. M1 charges no fees, not even trading fees, and it lets you borrow against your account with considerably low interest rates. Read more about M1 Finance in my company review and consider signing up for M1 today.
Businesses that start with a large audience are more likely to reach viral content fame organically (without paid tactics) because their audience propels their content forward. Businesses that are starting with a smaller audience may want to invest in paid promotion methods to ensure that their content reaches the most people possible to help it spread quickly.
Whereas Kaplan, Haenlein and others reduce the role of marketers to crafting the initial viral message and seeding it, futurist and sales and marketing analyst Marc Feldman, who conducted IMT Strategies' viral marketing study in 2001,[citation needed] carves a different role for marketers which pushes the 'art' of viral marketing much closer to 'science'.[23]