Not having gone past the front page, I much prefer the 'owe.to' approach to 'whosebill'. Having seen both of them for the very first time today, I can see myself using owe.to over whosebill 9 times out of 10.

That said, whosebill does seem to have a ton more features, but I prefer the narrower focus. The graphs on the whosebill homepage are confusing, even if they're only pictures.

It looks good. I wouldn't say that it's _pretty_, per se, but it's far from ugly, and appears to be 100% functional. Kudos.