Apart from what it displays directly, Disk Utility on Mac OS X (10.6, if it matters) keeps a log, visible through Window → Show Log (or ⌘L). This is probably a file on disk, right? Where is this file? I'd like to look at it if e.g. Disk Utility stops responding.
(I also don't know where the rest of the system logs are (probably /var/log, but I never know which files to look in), but that's probably another question.)