Link: Tagβulb - Tag Search Simplified. Interesting idea. This just searches on tags from a variety of tagging resources (except del.icio.us) and throws back a bunch of results to you. Results are clustered by type (audio/video etc) and then by resource.
Interesting way to run a search; I wouldn't want to rely on it, but for a lateral search or serendipity, it's worth a try.