"I like Facebook, I use it often. $365B... for a message board. Yes, I use it. Yes, I think it is useful. Yes, I think this valuation is absolutely crazy."

Not many todo lists have millions of users, including some that pay actual money for the service. Having looked at many project management tools, Trello has absolutely nailed certain aspects of the user experience that many of the others get wrong. Try pasting an image into a card, for example.

It's not a perfect tool, but if you tried to recreate it yourself, you'd probably start to realize why they netted $450M.