Jul 2015: Mu, a little virtual machine, operating system and programming language for teaching programming one-on-one (src)
Feb 2013: Wart, an experiment in making code accessible to outsiders. Emphasizes readability, lisp macros, extensible names, keyword args. (src; Nov '10)
Jun 2011: Google+ Circles, nuanced sharing with your network
I worked on scalably delivering posts to circles, and on real-time updates.
Sep 2010: Yam, a suite of scripts for querying webserver logs from the commandline
Mar 2008: Recommended, a social network for startups and investors
May 2007: Ph.D. dissertation, on prefetching for different access patterns (ISMM '06, SPEC '06, tr '02)
Dec 2004: Clickable links in VNC using bitmap matching for your font