UPD: FooSFX is deprecated, I’m not updating it, because built-in media search in Reaper is much better and convenient now.

FooSFX – it’s a pack of Foobar2000, made specially to help sound designers for searching through sound libraries.
I constructed it for myself as a free alternative to existing similar commercial products – I must admit that this searcher matches you if you store your sounds named like “water splash large.wav”, I mean if description of sound is in it’s wav-filename. I prefer this kind of organizing because if you use just metadata you can’t see visualy what sounds in this file move through file manager of you sound editor, daw, whatever, and besides, a lot of software can’t understand metadata rightly in case you want to change your search tool from one to another.
If you store your library in such formats like flac, ape, mp3, ogg etc which are supports tagging, with descriptions in tags, you’re also can use this searcher – it’s Foobar 😉
Besides, abilities of Foobar2000 give you a lot, and I can say even more than some commercial analogues. Just meet with the Foobar2000 features and it’s hundreds components – all of them you can use in your new searcher!

FooSFX is portable and works without installation, but you must set it up for yourself before, please read txt-file in archive.