Splitwise - Splitwise is a free tool for friends and roommates to track bills and other shared expenses, so that everyone gets paid back. On the web, iPhone, and Android!
Epihub - Shopify for tutoring, training, and online schools
Splittable - Shared living made simple
Traverse - Barcoding solution for small to midsize businesses
EquiTable - Split the bill fairly
DIY Air Purifier - Build your own air purifier for under $100