This seems like as good a forum to post this on as any;
I desperately need a good Diablo clone to play. I'm waiting for Diablo 3 obviously, but that's a long way off. Torchlight 2 is probably slightly nearer in release date, but still not out now.

Games that fit the bill in the past:
-Diablo II (obviously). Not old enough to have played Diablo 1, and it is too dated for my tastes now.
-Titan Quest. This was actually better at doing the diablo formula than Diablo II was, in my opinion. The sheer number of paths available in terms of character abilities and stuff was amazing. Was lacking in visual customization.
-Dragon Age to some degree. DA:O is much too tactical and story oriented to be considered a Diablo clone, but it had the elements I like (such as lotsa loot and ability variety). Not going to be playing DA2 from the sounds of the reviews.
-Fate/Torchlight. These are basically the same game, except that Torchlight has more content. They lacked multiplayer, and just had less content overall compared to Titan Quest and Diablo II though.
-Mount and Blade. Even less a Diablo clone than DA:O, but I think I fell in love with this game for similar reasons to the others. Particularly with an complete-overhaul mod installed, creating and "leveling up" your personal army was very fun in this game, and there was some cool loot to try and find.

Here's some qualities I've found I like about the Diablo-genre:
-Many opportunities to min/max my characters, with many layers of complexity to peel away when it comes to designing your ideal character. This was a poblem with Torchlight, as there wasn't much depth. It was what was RIGHT with Titan Quest. The idea of choosing two classes per character in Titan Quest really added to the value of that game.
-Plenty of loot. Yah, I'm shallow. Not gonna apologize it. I'm sure I'm part of the problem when it comes to lack of innovation in this genre, but I can't help it if I like collecting lots of items and get addicted to farming for better and better items.
-Visual customization. This goes hand in hand with the loot thing. I appreciate in a game the ability to make the character look your own.
-Not too hard. I like the idea that the worst that happens is that I have to chug more potions than normal and start hurting for money. Again, I know it may be shallow but I don't really want setbacks in my game. Challenge, on the other hand. I know this is cryptic, but let's hear what you think.

Note: these aren't the only types of games I like, it's just what I'm asking for help on right now.

Yes, on PC. Sorry I didn't make that clear. I'll look that one up, thanks. I'm aware of roguelikes, though I always had the impression that part of the criteria for being one was that you incorporated permanent-death and also high difficulty, neither of which sounds attractive. I know Diablo II had Hard core mode, is that what you're thinking of?

Ok, so it doesn't have loot, skill or character system, and there's almost nothing in terms of pickup, but still I'd say you gotta try Magicka if you haven't already, since it really nails the action part of the hack-n-slash games.

It's absolutely hilarious, great (dare I say innovative) game mechanics, and has good replayability if you want to use different spell combinations. Besides its cheap so you still have money for Diablo 3 or whatever else you find

http://www.magickagame.com/

Though they aren't exactly similar to Diablo(2), I always enjoyed the D&D games on PC along with Diablo and Diablo 2.
I also played the crap out of Tian Quest, Torchlight, and Fate.

My suggestions to you:
Icewind Dale 2
Diablo (it really isn't that dated since you can customize the classes to a certain extent since all can use all the spells, healer warrior anyone?)
WoW (if you are willing to pay the money :/ )
Neverwinter Nights
Sacred( heard it is really good as a Diablo style game)
Space Hack(also heard this is a really nice Diablo clone)

Anything that uses Advanced Dungeons and Dragons or Dungeons and Dragons 3rd is pretty good.

Ya, I tried Magicka. I appreciate it for its humor, but the light rpg elements lead me to not finish it. Thanks anyways.

Torchlight 2 /w multiplayer is due to be released soon. Other than that, this is what you might be looking for. Consider the second instalment.

In case you missed it, and since you said you really liked Titan Quest, you should also wait for Grim Dawn. It's made by the TQ team, which split and formed an "indy shop". So far I think it looks good.

http://grimdawn.com/