This article contains 10 handy CSS tips and tricks you might not know. Following on from that, there's some good corrections and amendments in the comments section, and then again
here.
Anyone who's developed a site for multiple browsers knows that there are so many hacks, workarounds, and browser compatiability issues with CSS - finding articles like these filled with comments and people disagreeing with methods reinforces that. Anyhow, some useful tips in there.