Calculate who should pay who and how much
Splitastic.com is free and helps you when you will compile who should pay what for a trip, excursion or similar.
In three steps, you specify what the bill is about, who should be involved and pay and the expenditure occurred. Then you get a list of who should pay how much and to whom. Splitastic.com also capable of compiling expenditure where only certain people participated.
Here you can see an example of a bill.
Step 1 (of 3): Enter the name of the bill
Find a name for this bill (eg Colorado trip, Beach party) and enter a password if you do not want others to see it.