Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.

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!

Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.

Dinngo - Splitting payments the fun and easy way

Strikethru - Strikethru is a kind of to-do list notebook for managing work lists and staying updated with the important tasks.

/Tab - The simple way to split a bill among friends.