I've seen so many web-collaborative-tool-browsing-do-das lately that I'm getting pretty jaded. I've already got a bunch of plug-ins and software and sites and whatevs installed/bookmarked/tagged to help me "do my research" and "share my ideas." I don't think I use.. well.. any of them. At least not regularly.
But I have to admit:
Twiddla sure will be very helpful when I start working on designs for the new Cost of Freedom magazine.
If you haven't seen ShiftSpace yet, it's kind of similar, but with much higher goals: basically, these guys want to open up the web. In addition to the usual annotation tool, ShiftSpace's image swaps and source code tweaks let users alter the image of websites, creating a second layer on top of any page that could present a radically different message than the controlled design. Neat idea. I'm really curious to see where it all goes.