Any time tracking ideas for a two-party, separate-machines, hard-to-coordinate household?

My wife and I have the need to track our time independently and yet work with it in the aggregate. Does anyone have something to suggest–possibly something web-based? The primary constraints for us are quick start-up, shallow learning curve, and data export to various formats.

Back in the day, I used a pad and every fifteen minutes made a hash mark next to what I’d done. It seemed to work pretty well, so far as billing was concerned. What’s your solution?