An album? Probably the Lord of the Rings soundtrack, seeing as that's like 150 tracks of fairly good, varied classical music.
As for ten songs:
Paint It Black, by The Rolling Stones
Stairway to Heaven, by Led Zeppelin
Lift Me Higher, by Poets of the Fall
Battery, by Metallica
Kickapoo, by Tenacious D
Tribute, by Tenacious D
The Final Showdown, by Tenacious D
The Ultimate Showdown of Ultimate Destiny, by someone i can't remember
Slaughter Your World, by LFG (Looking For Group)
Still Alive, by Jonathon Coulton (i.e. the portal ending song)
I chose those on the basis that they're all songs I could listen to a hundred times and never get bored of, which would be a good idea when you can only choose 10 tracks
It's also a list I will want to edit after ten seconds of posting this as I remember more songs I'd rather have there.