Colin mentioned an excellent use case for microformats to me: a standardized way of displaying information about music, most likely a direct one-to-one relation in XHTML of the ID3 data that is embedded in MP3 files today.
Since audio files are binary files, in many cases quite huge, having basic crawlers parse them to get this ID3 would introduce a ton of overhead. Having this available in a human-readable way that is also parse-able would be great.
I'm sure Colin will expand on this mini-post (nudge, nudge). Update: He did - Micro formats and audio = peanut butter and chocolate