Back in the day I used iTunes to manage my mp3s, used it to properly fill out their metadata, and then used it to rename all the files appropriately, but there’s tons of other software to do that.

I also lost the last 1/3 of my music library when my roommate spilled beer on my laptop (frying it), and then midway through transferring the files off I tripped on the usb cable and shattered the hard drive.