Well, I'm the author of the "CycliStats" ride log (
http://www.CycliStats.com), so that's what I use.
I log: Bike, Date, Distance, Time, Avg Speed, Calories, Climbing (elevation gain), Max Speed, Avg. Heart Rate, Max Heart Rate, Avg Watts, plus free-form Notes (for things I saw or felt, notes on intervals, etc.). Here's a screen shot:
http://www.shastasoftware.com/CycliStats/addride.htm
CycliStats also tracks my personal health stats (weight, blood pressure, resting heart rate, body fat %, etc.), and bike maintenance (how many miles on that rear tire or chain?). Plus, it features a bunch of reports and graphs for any bike and time frame, available with just a couple of mouse clicks.
If you're interested, you can download a free, fully functional 45-day trial version from the website.