I use Google WAVE a lot.
I don't use it as a collaborative tool much, though. I use it as a combination idea board and research file.
I have waves for subjects, like "sewing" and "health." I store links, snippets of text from articles I've read, brainstorming, to-do lists, questions, etc. in the subject waves. I can look at my waves from anywhere I can log on--at work during a break, at home, on my laptop while traveling. I can drop links in a wave for videos to watch later, articles to read later, stuff to buy later; I can drop a line of text that's tickling my thinking for writing a post later. I've got a wave for books I want to get from the library.
Try it, it's a useful tool.