Miu Tunes!!!!! GREAT program. Currently only in BETA but it makes your BB look like an iPod Touch or iPhone with cover flow graphics. Chaz posted the link above.
In addition to MiuTunes (which I think is pretty cool), there's also FlipSide. It's pretty good program. The recently released 1.14 version now appears to be linked to last.fm, so you can elect for music you play on your media card to scrobble to last.fm or any last.fm widgets you might have on a website, etc.