If you want the songs from Fallout 3 and you're too lazy to actually look at the track titles and artists, Bethesda has made your life a little easier with a Fallout 3 iMix. The publisher details here how you can get all those lovely Galaxy News Radio songs in one convenient download. Simply go to the iTunes store, look for the iMix section under "music", and do a search for "Fallout". Underneath all that Fallout Boy junk, you'll see a "Fallout 3" iMix of 13 Galaxy Radio songs guaranteed to put you in mind of a) wandering the Capital Wastelands, or b) smoking unfiltered Lucky Strikes, wearing fedoras, and coming home from World War II.
(Thanks to Brandon Boyer's consistently interesting Offworld).