I bit the bullet and picked up an SSD. It's expensive, but it had some surprising benefits. The normally quoted benefit is speed - which I really don't notice. Most operations went from some annoying amount of time, to some other annoying amount of time. I did notice two things:
1) Silence: I'm so used to hearing my laptop harddrive I couldn't figure out what I was missing - there is no more annoying grindings; clicking or whirring.
2) Coolness: SSD's run cooler - which means less spinning fan, which means more silence
UPDATE: The most valuable thing about the SSD is the harddrive doesn't die when I drop the laptop, if you don't have an SSD in your laptop it's totally worth it!
(Update: A short, highly entertaining talk about SSDs - mostly for servers here)