While at cabooseconf last month, I found out about one of the coolest time tracking tools ever: punch. (Thanks to cardiod from OG)
According to its own description, it's a
I find this to be a much easier method of tracking time than many alternatives, including the zillions of time tracking/billing web 2.0 sites. In fact, an hour or two of hacking could leave someone with a pretty decent time tracking AND invoicing tool.k.i.s.s. tool for tracking the hours spent on various projects. it supports logging hours under a project name, adding notes about work done during that period, and several very simple reporting tools that operate over a window of time.
And wouldn't ya know it, it's as simple as gem install punch.

So if you're using a time-tracking system, does that mean you've got some freelance side work?
Yeah, I've found that some freelance work keeps me focused on achieving extra goals (saving money, etc), and it has the added bonus of giving me a great excuse to learn all kinds of new stuff.