Yes, Daggerfall, by all means.
I've been hooked on video games since I was 4 years old (1986), and Daggerfall is still my favorite RPG of all time. It's got such huge depth (it takes an entire day in real-time to walk across the world, not even counting all the dungeon and city exploration), tons of lore, excellent music, wide variety of cultures/people to interact with, and tons of great gameplay mechanics (create custom spells, enchant weapons with custom spells, etc)...
It's an Elder Scrolls game, and I still prefer things about to its more recent relatives (Morrowind, Oblivion). They've removed tons of things in the newer games that were present in Daggerfall (certain days being holidays in towns with special events, worshipping and doing quests for certain gods or daedras in order to get weapons, etc, different religions and more guilds as well)...
Great game. Get Daggerfall if you ever see it somewhere. If it comes to GOG, I will buy it - even though I still have the CD in mint condition.

Shadow Caster was sort of like Stonekeep but it had an interesting concept of giving you shapeshifting powers with each shape having its own strengths and weaknesses. Plus Shadowcaster was made by Origin so you can't go wrong there.

The Dark Spire for the DS is supposed to be a great, old-school style Wizardry clone. I'd look into it.

Dungeon Master lost me a lot of sleep many years ago. Never did manage to finish it, used to get stuck in a corridor with no apparent way out, but this never stopped me going back to try again, totally addictive. It would be great if "GOG" could re-issue that game.
Mava

There is also Dungeon Hack by SSI. It was a first person dungeon crawler with a randomly generated dungeon. Lots of loot and enemies to kill.

Orcs & Elves for the Nintendo DS is awesome.

Indeed.
And the Dark Spire looks like it's going to be a good one in the same style as well.

PC:
Lands of Lore
Anvil of Dawn
GBA/NDS:
Mazes of Fate http://www.mazesoffate.com/

There is also Nemesis: A Wizardry Adventure. It has a single character and the POV is the same. I haven't played it in a long while but I think it might be what you are looking for as far as Stonekeep like games go...

In addition to this, the DS also has Etrian Odyssey 1 and 2, both of which are very similar to this.
As far as PC goes, my only confident recommendation would be Wizardry 8. It's from around 2001, so it's by no means difficult to get into or control when compared to some older titles. Runs easily under modern Windows systems, and even supports widescreen natively. The only problem is price; Amazon lists used copies as starting around $50, but it's truly a fantastic RPG, and I consider it the swan song of the sub-genre.

I think ultima 8 is one of the best old rpg games.
its not first person like stone keep its 3th person and in 2.5D
But its pretty nice

Ultima VIII aka Super Avatar World is AWFUL. The last decent Ultima(and maybe best overall) were the games in the VII series.

Very similar games (fpp and step-wise movement):
- Dungeon Master
- Chaos Strikes Back (Dungeon Master expansion)
- Dungeon Master 2 (not nearly as good as the first one, but still)
- Bloodwych (released shortly after Dungeon Master 1, offering a coop mode)
- Might and Magic up to and including part 5
- Eye of the Beholder series
- Anvil of Dawn
- Wizardry series
FPP RPGs with "free" movement:
- Ultima Underworld 1 and 2
- System Shock 1
- Lands of Lore 2
- Daggerfall (now free)
I know that most of the games were already mentioned, just wanted to compile a list in one spot.

That is true! Arx Fatalis, and then Dark Messiah of Might and Magic are close to the idea of Stonekeep. I am Stonekeep fan and when i found those two games, I loved it at first sight. I hope new Arkane Studio's game - Dishonored, will be as good as rest.

Doesn't look like Legend of Grimrock has been mentioned yet. It's a new indie game that's done in the style of games like Dungeon Master or Stonekeep, and it's available right here on GOG (as well as other distributors).