I agree - I've seen some pretty good points made here. Most of my pastimes are solo (reading, computer, learning to play guitar, motorcycling, scuba/sky diving), and I don't often have time to pursue them even so - especially in the middle of the prairies winter!!
Some of the ones I hadn't actually thought of include the volunteer / charity work suggestion. That seems like an excellent way to address a few things at once - I have charitable causes that I'm passionate about but just haven't taken the time to get really involved. I guess I forgot there's more to charity than giving money...
You've already given me lots of good suggestions. Thanks guys!