Explore any site from the Web 2.0 awards list, play with it and write a blog post about your findings.
The Web 2.0 awards list is now offline, but there are still ways to monitor and gauge innovations in online collaboration. Almost every professional organization worldwide has a mechanism for recognizing and rewarding new Web tools that build community and accomplishments.
For libraries, a good place to look for exceptional tools is on the ALA's TechSource site.