Chris at Adventures in Capitalism has an interesting idea for a local blog aggregator business:
Just put in your city or zipcode, and the service generates a special page of content with latest and greatest posts by bloggers in your area, or mentioning your area.
You could use algorithms to decide which posts were most relevant based on trackbacks, comments, etc.
People could also add their own blog to the geographical index.
Given all the emphasis on local search and blogging, it sounds like a sure buzzword bingo winner to me!
Remember, ideas are easy. Execution is what matters.