"I had the idea of Short Reckonings when I was a student and was often sharing expenses with friends. Having such a tool at the time would have been great but this was before the Web."
Users of Short Reckonings first create an expense sheet and the group of people associated with it. Then they enter each expense, indicating who paid how much for what and for whom. Finally, Short Reckonings calculates the fewest number of payments needed to even the debts back out for each person.
The level of customization of the widgets is excellent, especially with the custom events.
Mikaël was born in France and moved to Canada in the late '90's where he co-founded Webmotion. His latest project is a free collaborative Web 2.0 tool called Taskado which also relies heavily on YUI.
Both apps are available in the YDN Gallery.