stagetimer.io - A speaker timer in the Cloud
Particlescape - Particlescape app lets you create stunning patterns at your fingertips.
Pencil - Pencil is an animation/drawing software for Mac OS X, Windows, and Linux.
TripleA - TripleA is a free (under GPL) turn based strategy game based on Axis & Allies board game.
Email Taco - A free email countdown timer for expiring offers
Fluid dynamics - Fluid dynamics developed and published by Reinder Nijhoff.