I have a 20GB Creative Zen Touch, and apart from my telescope, its the best purchase I've ever made. Keeps lots of songs, and has lots of room to store things.
However, I am guessing thats not what you're after. I would suggest one of those new Irivers with the cool video screen for pictures, so you can show work mates some of your space pictures (

) but if you don't really care much for that, then a simple mp3 player would do.
One thing about creative brand - check to make sure it doesn't use the 'nomad explorer' application if you are going to purchase one. My creative player isn't plug and play, ie. the computer needs the program installed to use it (making it a nuience to use in other computers) and even then, it doesn't just pop up on screen when connected allowing easy access. Though I must say, this is one of the only negative things about my player.
Hope this sorta helps... though I've kinda gone off track.
EDIT: Forgot to mention - I bought my Creative Zen Touch about half way through last year, and it cost about $500. Therefore, a >1Gig should be a lot cheaper! (plus ordinary electronics cost decrease).