Lunchclub - Curated 1:1 professional connections
Caliber - IM for LinkedIn. Instantly chat with your business contacts.
Serendipity - Serendipity is a PHP-powered weblog engine which gives the user an easy way to maintain a blog.
Until - Until lets you create beautiful widgets to count down the days until meaningful events in your life.
Lunch Roulette - Collaboration by grouping coworkers randomly for lunch.
Founders Cafe - Co-work with Founders from Stanford, YC, Harvard