While Kelly Gallagher may not be a "Web 2.0 Tool," his website is a wonderful resource. I had the pleasure of attending one of his workshops on reading comprehension strategies, and I have been using his Article of the Week database ever since. Gallagher and his coworkers post PDF files of nonfiction articles on current event topics. I have students highlight main ideas, new words, and areas of confusion; they also annotate passages in the margins and then write a brief response to the articles. This is an excellent source for "beefing up" the nonfiction component in your curriculum.
Dr. Jessica Pilgreen, Ed.D.