When I'm not working, I have a tendency to meddle in bug reports on Meta or take part in writing userscripts for the Stack Exchange network which add features that sometimes get implemented natively. Here's a few you may be interested in:

• Autoconversion of bare Stack Exchange URLs in comments
• Keyboard navigation and /commands for chat
• Enhancements to the network reputation graph
• Stack Overflow/Stack Exchange reputation/moderator status display on Meta Stack Overflow

I've also been known to occasionally break (and sometimes fix!) the Data Explorer, and to busy myself with maintaining the Election Statistics page.