I believe strongly in free culture and free-as-in-freedom software. Here are some open source projects I maintain:

Active

Falling Fruit - The source-code behind the non-profit website FallingFruit.org, a platform for collaborating on a massive worldwide map of free food.

Food Rescue Robot - Logistics software for tracking decentralized food recovery. Originally developed for Boulder Food Rescue, now used by a dozen or more organizations in cities around the US for managing their operations.

Small White Cube - This website :)

Stable

Parallel SSA - Code to perform spatial simulated annealing (SSA) in parallel on a compute cluster. Geared towards optimized sampling for my dissertation research.

The Second Kitchen - Web-based inventory tracking and point-of-sale system for a food buying cooperative in Boulder, Colorado. Now used by an organization in Denver as well.

Path Loss Research Utilities - A motley collection of useful programs for doing research on path loss models.

QualNet Hacks - Useful hacks and additions for the QualNet 4.5 simulator including EDAM (Effective Directivity Antenna Model).

Traffic Simulation and Classification Software - A framework for generating real-as-in-really-real workloads in simulations of infrastructure wireless networks.

Stochastic Similarity - Matlab code to implement the stochastic similarity metric of Nechyba et al..