Splitwise - Splitwise is a free tool for friends and roommates to track bills and other shared expenses, so that everyone gets paid back. On the web, iPhone, and Android!
Vrbo - With over 2 million bookable vacation rentals, Vrbo connects homeowners with families and vacationers looking for something more than a hotel for their trip.
Kittysplit - The easiest way of sharing costs with a group of friends
Booking.com - Find your next stay. Search deals on hotels, homes, and much more...
ihatemoney - Manage your shared expenses, easily
Airbnb - Book unique places to stay and things to do.