Spectrum - Browser-based app to visualize the frequencies of an audio file.

Q-Stats - Get free marketing insights for every question on Quora.

Roomvine - Chatrooms for real life venues, neighborhoods and events

Site Rank Data - View historical rank information of websites via time series charts.

Treadie - Create your own micro-social network for topics

Seoxan - check seo report for any website, alexa ranking, server information, meta tags, authority, page speed and more