Ask HN: Most successful startups launched during tech conferences?

Demo, Techcrunch50, Web 2.0 ... you name it, tech conferences are (said to be) a great way for startups to go to the next level, network, find investors etc.

What are the most successful statups launch in this kind of conferences over the last 3 years :

- in term of profitability today ? - in term of market share or other important metric of success ?

I think it's important to look back at those and try to understand what key aspects they share in common.