Virtually every audio jukebox program--such as iTunes or Windows Media Player--has effective tag-editing capabilities, which helps you customize or standardize your entire music collection. There are some programs, though, that do tagging better than others. Yahoo Musicmatch Jukebox Plus 10's ($20) batch-friendly Super Tagging utilizes its database to fill in tag info automatically. MediaMonkey (free to try, $20 to buy) is a Windows-only audio jukebox that's compatible with many formats and includes intelligent and automatic tag editing. And if you're looking for a nice, free editor, check out MP3 Tag Tools. For a cool (and also free) Mac editor, check out iEatBrainz.