Every week or two I clean the chain with one of those finish line chain cleaner. It's pretty messy - I imagine it would be cleaner with a derailer, but oh well. I lub the chain about once a week, more if the weather is bad. If I have time or I'm bored when I clean the chain I floss the cogs and chainring with an old rag.

I clean the frame/seatpost every week or so, usually with just a wet rag. If I'm really ambitous I'll take windex to it. I take the wheels of when I do this so I can get into all the nooks and crannies. I don't clean the rims quite as often, but try to keep them pretty clean. I took some steel wool SOS pads to them about a month ago - the front one was looking pretty sad after a couple of winters. I plan on taking some fine grit sandpaper to them to get all of the discoloration and the marks from when I ran a front brake off before this winter hits.

As far as winter maint, I don't usually do much at all, but the winters are pretty harsh here. I usually leave the bike locked outside for almost all of it, so the snow and salt don't melt. It not only makes a mess when you bring the bike in, it rusts out your bearings quicker. The salt doesn't really get into the threads if it's embedded in the snow - it's when it melts that you have trouble.

I check my headset tightness and the lockrings on my rear wheel about every two weeks (usually when I'm cleaning the chain since the wheel is aready off). I need to get myself a set of cone wrenches so I can check those too. I'd also like to get a truing stand so I can check my wheels every month or so, but haven't had the money.

Oh, and I check the tire pressure every couple of days since I finally bought a floor pump. It could be a coincidence, but I haven't had a flat since I started doing that...

There's probably more that I should do, but that's what I DO do...