I recently launched FaveBot.com, which I think is a great tool for bloggers to keep up to date on whatever topic(s) they blog about.
FaveBot enables you to continuously discover new content and/or events matching your interests. Just set up a list of topics/things they want to track and FaveBot searches the web daily and returns a stream of matching content. That content could be any of the following: local events, new releases (book, CDs/MP3s, DVDs), podcasts, online video, news, photos or blog posts.
You can get RSS feeds for whatever you're tracking and put them directly on your blog to provide fresh content to your readers.