Another vote for Fret Doctor. It's almost useless to post it after so many people have done so, but man it's incredible stuff! It's like $12 a bottle, but my bottle has lasted about 2 years (at least 30 applications). Still have a lot left too.
Sometimes I see Gibsons on musiciansfriend.com or some other site, and the board is all dull, dry and terrible looking. Why don't they oil the poor boards!? Insane.