hey i was just wondering what is in the secret dungeons? is there anything worthwhile like cool monsters that we wouldn't see above ground, or good items to snag? i looked at the maps for them and they look quite complicated to explore but if they're worth it i just might have to
thanks

Monsters - i like the Killer Kubes. Aside from this (and some uniques), no new monster types (but athrrazite golems and the like, which doesn't appear elsewhere)

Items - IIRC graveyard dungeon has nothing important. Northern has several plate mail +2/+3, a plague axe, among others. Mountain has the unique Amulet of Nebdar (from the unique Nebdar), which is very nice for spellcasters. And IIRC the Ripper (second best axe), but this is found in other places too. And more useless high level stuff.

See the "I want in" thread for more info.