Since my last request went over like a lead balloon (
http://getmusicbee.com/forum/index.php?topic=18669.msg112522#msg112522), I'll try to make it more generalized.
I've always like mp3tag's $regexp(x,expr,repl) (for purposes here, x=field; expr=regular expression; repl=replacement regex). I'd simply like to have more ways of customizing my virtual tag output and regexpreplace should be able to accomplish just that.