My take on the problem has been live since end November (yeah, working on the marketing & design side now). http://splitsies.net/
Android please. :)
Edit: I signed up. Looks like it -just- does splits, and not separate IOUs. Unless I say that I paid, but the cost goes to someone else?
Might be worth having a separate IOU interface to save confusion.
Just a thought. :)
(edit to respond to edit)
What do you mean "just does splits"? It doesn't (at the moment) do a good job of explaining that the IOUs balance each other out: if I buy you lunch, then you buy me lunch, we're probably pretty close to balanced out.
I'm working with a great designer at the moment to try and fix some of the programmer-isms in the UI.
But it hurts my head to work that logic out, for some reason.
And yes, we've got a way clearer and sexier UI in the pipeline.