If you don't already have them, fenders go a long way towards decreasing the amount of maintenance you'll need to do (that is, if you ride in the rain/slush). Not only do they keep a lot of splashing off of you, but a lot of that splashing ends up on the drive train, and if you're in snow-prone areas, a lot of that splashing is a saltly, cindery solution that is definitely bad for your bike.

I do very little maintenance on my commuter: I periodically wipe down the chain and cogs with and old rag and lightly relube. I only very rarely (once or twice per year?) take the chain off for a thorough cleaning. To be honest, I often go quite a while without doing anything. If anything feels funny or squeaks then I take a harder look.