Regarde Simple access to several MP3-related search engines one at a time. Plus good background information on the MP3 format. SavvySearch MP3 A meta searcher which searches 8 popular MP3 search engines. Net Multimedia search engine for audio, video and images. Not a search engine itself.
Form can call multiple search engines simultaneously.
SearchFast for MP3s Search from a list of popular MP3 searches. SeekMP3.Com MP3 meta-search engine. Also includes a browsable archive and links to tools, skins, hardware and software. SilverSearch MP3 Meta-search engine that searches for MPEG layer 3 files by looking through other search engines. You can optionally give it your email address and it will mail you the results when its done.