Instead of kill -9 (a nuke), you can often get results with just kill, kill -INT or kill -HUP. (The advantage is that the "weaker" signals allow your runaway program to do some cleanup, but kill -9 doesn't.)

There's a nice write-up and a function automating attempts to run increasingly strong signals on this site: http://web.archive.org/web/20080610070315/http://sial.org/ho...

(Thank god for the wayback machine. That site was full of good Unix tips and tutorials, but it's gone now.)