When brainstorming for viral marketing ideas a good route to go is to solve a problem for current or future customers. One benefit of creating something that solves a problem is people will be more likely to spread it to friends, family and colleagues. They will also bookmark the resource or tool.

Remember how success Hotmail’s viral marketing campaign was when they simply included “Get your private, free email at http://www.hotmail.com” in each email.

- They solved a user’s problem. People did not want to pay a company for an email address or change their email every time they switched internet providers.
- They made it easy for the user to spread.

Viral marketing does not need to be complicated. In fact, often the simpler it is the better.

Seth Godin has a great post on What Makes an Idea Viral?