Lunchclub - Curated 1:1 professional connections
tripcake - Doodle for travel plans with friends
Serendipity - Serendipity is a PHP-powered weblog engine which gives the user an easy way to maintain a blog.
DUNK - Surprise your friends with secret group plans
Coworker Coffee - Coffee with a different coworker each week
Howbout - Social calendar app to easily make plans & find availability