Periodic Maintenance Task for Bike Commuters
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.