I only just found this thread, but I've actually been logging my bike trips all month. I'm lucky enough to live in Portland, Oregon, where we have the Bike Commute Challenge for the city every September. There is support for new riders, snack stations on major routes, and lots of prizes at the end!
Portland is a super bikey places, and my primary transport has been cycling for the 10 years I've lived here, but September has been a big challenge for me. I just started a new job after working from home for 5 years (only biking for errands/fun). I'm really happy to have to get out and ride every day. It's even downhill on the way to work, so I arrive awake with a healthy glow (the ride home is slower and my healthy glow is a more of a sweaty lobster). Personal savings = $100/mo bus pass, $35/mo gym membership, and its twice as fast as the bus!
I've added my trips to the spreadsheet, and updated the formulas to include all rows on the main sheet.
To young_one: I also vote Ortlieb. All my stuff is dry even in a downpour today. Got a pair off a friend for $80, but I've also seen them on CL for reasonable amounts. I am much more empowered to ride when I'm not afraid of the weather or being weighed down by a messenger bag.