If you want some atmosphere of "I have been cast here for my sins, and by exploring I am to repent", you can try this one:
http://studioeres.com/immortal/soundtrackThe soundtrack for a tower defense game galled "Immortal Defense", as sad and noble as the game itself.
Also, perhaps I could suggest not an album, but rather a program to generate the ambient.
http://umopit.ru/AuraEng.htmThis nifty program can sit in your tray and fill your room with sounds of forest: birds singing, campfire crackling, creek flowing, rain falling serenity - somewhat a resemblance of thoughts your adventurer could have while resting on the cold dungeon floor.
Also
HUGE PROPS to Minmay. =) I listen to
Nectarine Demoscene Radio sometimes, but the blips distract me from pondering on the situation. Cheibriados' followers definitely have a reason to move slow and to strike those who act too fast...
Also I listen to a Russian band called "Аквариум" (Aquarium), which is a mix between rock, instrumental music, new age, reggae and meditative music. Their leader, БГ, sings about various things, and their songs sometimes are too elaborate to understand from the first attempt, but listening to the music is interesting.
You can tune on to their songs here:
http://www.101.ru/?an=port_channel_mp3& ... it=2&fav=1 (some advertisements are blocking the way: click the dash-underlined link to proceed)
Though their music is not to be listening to all the time.