I've been hearing more about Stikkit lately. Basically it allows you create smart post-it notes. They can parse various things in the note to allow for collaboration and productivity.
Merlin Mann gives a great introduction and overview, showing all the ways a Stikkit can help keep you on track.
There is also now an API which gives me something else to investigate.
More about Stikkit from Stowe Boyd
Technorati Tags:
stikkit, stikkit+api