I've been having issues with the Topic Exchange recently -- something I've done has made it so that it tries to start the SCGI daemon, but fails, and keeps going round and round trying to restart it, while Apache gets stuck waiting for it with all its processes. I don't currently have any way of noticing when this happens (apart from helpful people sending me e-mails - thanks guys!).
That said, I recently installed MRTG, which gives me a nice graph of bandwidth over time. Checking just now, after clearing one of the aforementioned blockages, I saw this:
Hmm, a day or so of downtime. Ouch. Anyway, the MRTG log is my browser homepage now, so I should catch this sort of thing a little quicker now. Also, it looks like it happened exactly at midnight - so I can now go through my crontab and figure out what it is that is killing the ITE. Perhaps it's not restarting right after log rotation?