One of my co-workers turned me on to the bikejournal web site/application. If you’re a cyclist, it’s well worth your attention!
The site allows you to record all your rides, with as little or as much detail as you wish. I’m using my ride journal to track most of the data that my cycle computer provides along with notes on the weather. (20°C/68°F in February–I love living in central California!) The journal allows you to record which bike you use on each ride (if you have multiple bikes). It can even be used to track which tires are on your bikes, and how much wear they have accumulated.
One of the things I really like about the journal is planning for organized rides such as the Sierra Century. If you track all of your organized rides using bikejournal, your “century calendar” is only a mouse-click away. You can also see which other bikejournal-users are participating in the same rides, which might make finding car-pool buddies easier.
The site is free, but registration is required. (If you do register, check out my profile and send me a “buddy request”.) Some of the features are only available to “premier members”, i.e. those who pay $20 yearly support. For instance, as a premier member I can make my public profile viewable by non-members. I think the site is worthy of support, so I went ahead and paid for 3 years (and got a 20% discount). I don’t really need the “premier” features, but the publicly viewable profile is nice to have.