Don't have an iPod, or it doesn't hold enough? Here's an easy and relatively cheap way to make your own hard drive jukebox. I use this to take a bunch of my (legally ripped from CDs owned by me) mp3s to work with me.
Take an internal hard drive. I've got a bunch of 128GB ones sitting around from old projects; I also had a couple of laptop drives (…which I got at a friend's garage sale for $5). You could also buy a new internal hard drive, they're really really inexpensive. The drive should be at least large enough to hold your entire MP3 collection; the bigger the better.
Get a USB container for it; Fry's has these for about $30 (I got a fine 2 1/2 for $10); or if you like the naked look, just get a USB-IDE adapter cable for around $20. You could even get a standard external drive if you find a cheap one that you feel like dragging around; usually they cost more than an internal plus a cheap case. I believe most of these cases are “plug and play” – you don't have to install software; just plug it in. They also have cases to put the drive in if you're worried about dropping it or banging it around; which you shouldn't be because it's just a backup, right?
Format the drive (MacOS if you won't ever plug this into a Windows machine; otherwise DOS so it can be recognized by either). Copy all your MP3s. Take it to work, plug it in and install iTunes. Listen to your music all week long.
Do not let a friend “borrow” this drive (or just swap cheap drives with them) because they'd be able to browse your music collection (and you, theirs). This would be wrong.