I'm looking to add metadata to my library of effects. Which program are you using to embed metadata in wav files? Is this metadata readable by most database programs? (Soundminer, Basehead, etc.)
Birdhousesound's links are definitely good spots to start, but If you are purely interested in programmes dedicated to embedding metatadata, without having all the other bells and whistles... then you have these options that I know of:
Wave Agent: Free; made by Sound Devices; you can manually add the metadata yourself to each file. It's quick and easy to use, but although you can batch process, you are still limited to doing one file at a time if you have different metadata per file.
Injector Pro: $199; made by the same guys as Basehead; what's really nice about this is that you can have all your metadata in an Excel sheet and it will combine your X number of lines of metadata with your X number of audio files... Basically you can spend years building up a library and adding the metadata to your Excel file and then when your files are done and mastered, you can just "inject" them.
Your DAW: Chances are, when exporting your file out of your DAW you will be able to add some metadata too... quite painful though.
There are a million other pieces of software that do this too, but as Birdhousesound said, you can read about them in other threads.