Summize lets you search on a word and it brings up the recent tweets which has that word. It also offers "Trending Topics" which let you know which topics are hot at that particular moment. It's just one of a family of products from the Summize labs. Others are Realtime Sentiment where you input a word and the program reports how those talking about that subject feel about the word. For instance I put in "love" and it reported that the prevalent attitude toward this word was "great" (the highest grade). I put in "hate crimes" and the attitude was wretched, the worst grade.
Reviews, potentially very interesting, it summarizes attitudes and opinions from millions upon millions of comments throughout the web. (47,056,81 at this particular time). You can query for movies, books, music and interesting data magically appears. This is the search result for Madonna it provides opinions on all her products and even shows which bloggers are talking about her the most. Blogger Trends is another way of parsing the review data. It's like a techmeme for entertainment only done automatically which is fairer and while the numbers of sentiments look small, the results look fairly representative. And finally you can find reviews on the iPhone.