Sick of yellow sticky tags? Tada! (Wickedkitten)

Sick of yellow sticky tags? Tada!:

"From the fine folks that brought you Basecamp, the almost revolutionary web-based project management application that gave birth to Ruby on Rails, comes Tada — a simple yet powerful way to get rid of randomly placed files or tags or knots in your handkerchief to make you remember something you truly have to get done.
Tada is based on an extracted feature-set from Basecamp albeit building on some of the recently added features in Ruby on Rails 0.9. It comes with an impressive sharing feature that allows you to either selectively or publicly share your todo items (or impress someone with an empty todo list! ha!) so that colleagues and co-workers may collaborate on a single list.
Following Google’s Suggest Beta on the path of making extensive use of XMLHttpRequest, Tada makes use of this technique to resemble certain desktop applications in that it doesn’t throw a boatload of reloads and submit buttons at you while you’re maintaining your tasks. As such, working with Tada is a pretty convenient experience, given that it’s web-only.
Using the service is free, you’re limited to 10 separate todo lists though. Get signed up while your favorite user account is still vacant!
[Update 20/01: David posted a few more technical details over at Riding Rails"]