North Korea - South Korea Border Regions Travel Guide

If you are doing a day trip into Kaesong (Gaeseong) then bring your mp3 player (the bus ride is a bit boring on the SK side) and whatever because there are plenty of secure lockers in the South Korean immigration facility.  Do remember to go back to the lockers when you get back to the south!
Also there is a money exchange facility in the SK immigration building - which was open before we arrived.
Opposite the secure lockers (upstairs) there was a gift shop which had lots of drinks, snacks and a few bread items.  Really appreciated for a 6am start!

fantastic, though tourist-overridden mountain resort in 'north korea,' actually land rented by the hyundai corporation. if you go, you should have no trouble climbing the rugged moutain, because metal poles and stairs have been incessantly installed everywhere, so everyone can do it and enjoy the views of the east sea from the summit. try to practice your korean before you go, you might actually be able to speak to a north korean on the trail. they're the ones wearing the red lapel pins.

I went with Adventure Korea and they were great!
www.adventurekorea.com

We had an English speaking guide who was very personable and took us up the mountain to a spectacular view.

Interestingly, we were one of the few groups who stayed in a hotel staffed by North Koreans.. so it was a rare chance to interact with locals without the heavies watching every syllable.