Brightkite

Brightkite

Entrepreneur: Martin May, 30

Funding: $1.1 million from Techstars and undisclosed private investors; acquired for an undisclosed price in April by Limbo, which itself has received $24 million in funding from Azure Capital Partners, Draper Fisher Jurvetson, New Enterprise Associates, and Nexit Ventures

Dozens of startups offer mobile location-based applications, but few have gained wide traction. Brightkite amassed a big enough following that by April it was bought by Limbo. Now, Brightkite founder Martin May is charged with merging the two products, both of which let users add notes and see others' posts on such locales as restaurants or music festivals. Atop May's agenda: adding tools to help similar users discover each other and testing ads that target people based on preferences and location. The new company has more than 2 million users.

Lessons learned: "It's a lot harder to raise money in the downturn. You need to make sure that you have a way to differentiate yourself. For anybody thinking about a new startup, I'd recommend getting to a prototype stage earlier and show you can make revenue and show you have traction."