Coworker Coffee - Coffee with a different coworker each week
Shapr - A completely free way to build your professional network.
Serendipity - Serendipity is a PHP-powered weblog engine which gives the user an easy way to maintain a blog.
LetsLunch - Do more with your lunch hour. Meet new people.
Twine - Twine is an open-source tool for telling interactive, nonlinear stories.
Wildcard - Discover, connect and meet people at communities