We use Asana and are happy with it. It's free so I didn't include it (but maybe I should have).
I keep hearing asana... I like the keyboard shortcuts, so I'll probably go that way. Thanks!
We're using Asana at http://starstreet.com and are liking it a lot. That said, if we weren't already used to it and were starting today we may go with trello.
Trello has worked beautifully for this
Acunote works great for us (and is free for 5 users).