I've got to say I'm a huge fan of the wiki. Aside from Wikipedia, the first time I was really introduced to using them was last fall with Google Docs. I thought it was incredible that I could work on what looked like a Word document and others could at the same time, as well. I think they are such a helpful tool for students -- especially when it comes to group work. As for the library world, the library I work at uses them for trouble-shooting computer issues and FAQs at the reference desk. And I really think they're taking off when it comes to teen book reviews. Sooo helpful and fun.
I was not so convinced about the effectiveness of the PBwiki. Maybe it was because I found the layout to be pretty boring, or maybe it's just because there are so many specialized web sites out there that cater to people's individualized taste, but I don't think I would use this site very often. I was just browsing through some of the various favorite sites, and the interests are just all across the board, but maybe it could be more useful when helping out people with very different tastes. I suppose in that way, it could work similarly to the tools offered through Amazon, but I'm pretty sure I would just go with Amazon. I may play around with it a little more to see if I can find some of the site's greater strengths. The idea is good, but I'm just not sure if I would turn to this site for anything.