What are the periodic maintenance tasks (weekly, monthly, annual, every X miles) that anyone who relies on a bike for transportation (typically in urban/semi-urban environments) should be performing? Ideally stated in terms of miles travelled (where applicable).
My bike service guys wrote a blog article along these lines. You may find it useful: http://www.southcoastbikes.co.uk/articles.asp?article=Care
Edit I agree with http://meta.bicycles.stackexchange.com/questions/28/avoiding-just-buy-a-new-one-or-heres-a-link-answers - so in this sprirt...
The South Coast Bikes article recommends four principals for basic bike care. These are
Mostly it depends on where and how far you commute, and road conditions (sandy, snow, salt etc etc).
At a minimum what I do is:
Daily: check tire air pressure.
Weekly: Check brake pad wear, tire wear, clean/wipe down entire bike
Monthly: Check chain tension, chainring/cogs for wear, lube chain, adjust brakes, oil all pivot points on derailleurs, brakes etc.
Annually: complete tear down, inspection and reassembly with synthetic grease on all bearings.
Being a big guy (~400lbs) I do a lot of damamge to my bikes, so I check things more often, and most of the time there isn't a problem, just better to double check. So as a result, here is my paranoid check schedule:
Every 3 rides:
Every 3 months: