Here is a nice list from 100 Blog Topics I hope you write.
People often ask me how I come up with things to blog about, and I find the question strange, because my problem is the opposite. I have too much to blog about.
The nice thing about this list is that you and I can take the same topic and may end up writing very different things. I wonder whether there is a way to track how many of these ideas got blogged about. In fact, it may be a good idea to have a blog for each idea with a link to all the blogs about the idea.