My most extensive personal project to date has been my Masters Thesis. My thesis proposed a technique for speeding up web browsing over mobile networks through a proxy server that scans server responses and pushes content to the user just-in-time, and involved the construction of a Node.js proxy and Google Chrome browser extension for measurement. All of the intricate details are in Just-In-Time Push Prefetching: Accelerating the Mobile Web.
Unsurprisingly, you learn quite a number of things in Engineering that you'd never expect to learn. What is surprising is the variety and peculiarity of things that you do actually get taught. After a lengthy conversation about the things we had "learned", I threw together a page of items in the (then) style of the UW first year information package so that prospective students might get a complete idea of all the things they might learn at UW.
UW Computer Engineers will all remember the Coldfire boards, the lovely hardware units that we got to write an operating system for. To commemorate the - ahem, entire week - of my life that I lost thanks to the experience, I designed a desktop background.
When I was just starting out with WPF, I wanted to get a bit more experience with WPF Animation, and so I took a Saturday morning to build a neat little move-style title animator. It animates a series of "titles", a position/name string, on to a black screen at a configurable interval; more details, and a link to the source, are on the WPF Title Animator page.