I find that I worry a lot less about checking up on background tasks (compiles, laundry, baking pies, brewing tea, etc.) if I know I'll get a clear notification when the process is complete. If it's something that takes a fixed amount of time I'll usually just set a timer on my phone — this is a new habit that works well for tea in particular. Incidentally, owning an iPhone has done a surprising amount for my effectiveness just by reducing trivial inconveniences for this sort of thing.

For compiles, do something like

$ make; growlnotify -m "compile done!"

or run a script that sends you an SMS or something. This is something that I'm not in the habit of doing, but I just wrote myself a note to figure something out when I get into work on Monday.[1] (For most of my builds it's already taken care of, since it brings up a window when it's done. This would be for things like building the server, which runs in a terminal, and for svn updates, which are often glacial.)

[1] This is another thing that helps me a lot. Write things down in a place that you look at regularly. Could be a calendar app, could be a text file in Dropbox, whatever.