[bennesvig]

I'd think building virality into a product or service is one of the cheaper ways of acquiring customers. If you create something that works on its own, but is more fun when friends are using it, people are going to do the marketing for you. Instagram is a great example.

[fizzbar]

"Virality" is not something anyone has figured out how to bottle up and reproduce (and if they have, they're not sharing).

The music industry analogy would be to say "just make all your songs into hit records, that's how you get listeners".