Todo.txt - Track your tasks and projects in a plain text file, todo.txt. A todo.
Tricount - Manage and share expenses with friends
Task Coach - Task Coach is a simple open source todo manager to keep track of personal tasks and todo lists.
Kittysplit - The easiest way of sharing costs with a group of friends
Strikethru - Strikethru is a kind of to-do list notebook for managing work lists and staying updated with the important tasks.
ihatemoney - Manage your shared expenses, easily