Multitasking sucks.
Most of my work, both in grad school and after, has required waiting around for programs to compile, database queries to finish, and analysis code to finish processing a dataset. I try to do useful things with that interstitial time, but it’s hard to really focus when you have to check on the background task every few minutes.
I can’t solve this problem everywhere, but I can when I’m working with Mathematica. Notify is a Mathematica package that sends notification events to Growl when a long evaluation finishes.