I created this at the company I worked at a while ago:

http://stufftodo.dedasys.com/

It's basically a fancy todo list with sharing between people. I decided to open source it after seeing that there wasn't a lot of interest, and moving on from that company (I developed it on my own, so I own the rights to it). It's probably not right for everyone, but I use it and like it as it's very simple and direct.