I have grown to really like liveTopics. Converting from Radio’s categories to liveTopics has been cumbersome (as it matures, I imagine Matt might offer a conversion utility), but worth it. You can now browse a topical outline of all posts on this site here; it is now complete for July and August. I will periodically go back and add past months as well.
Even if you’re not very interested in sharing your topics (you can keep them entirely private), I’ve found they’re a great way for keeping track of past posts. When I want to pull up a post I made in the past, I just need to open the allTopics.opml file on my desktop and can immediately see when I made the post (and link to it from the file).
Of course, the advantages to your readers – if you’re interested in giving people an easy-to-navigate road-map to your posts – are big as well. In all, liveTopics is a great tool.