I like...
Persona 3 - not the recent P3 and P4, I want a sequel based on Persona 2 system and story but ATLUS never make it. Persona 2 was the best PS game I've ever played.
Torment 2 - or maybe a remake, see even now Fallout has its next-gen version.
Oh, and Vampire Bloodlines :P I love Masquerade though it's buggy.

You have played Max Payne 2 right?
And MP3 is rumoured to be in development.

I love lots of these selections. Ones that were mentioned that I would love to see...
1. Eternal Darkness: Just a great game. One I've played through several times. the story was quite good and I loved the sanity effects as well. It was great seeing the guy's head explode...
2. Space Quest: Another great set of adventure games. I played through 4 a couple of times. I want to pick up the package deal they have but just haven't gotten around to it...
New ones:
1. Zork: I would love to see a new Zork game. I still play through many of the originals when I get a chance. I loved Grand Inquisitor and spent a few days trying to get it to work properly on one of my new machines. I was so glad when it did. these games just had fun stories and a great sense of humor. I'd recommend these games to anyone.
2. Tie Fighter: I know a few people mentioned X-wing and I loved that game too. but being able to be the bad guys was so much fun. Especially having to fly an unshielded Tie, that was one of the toughest experiences to get through with out taking more than a couple of hits. I would definitely like to see a Star Wars space sim set in the new trilogy. Expand on the space combat of battlegrounds 2...
Finally, I'm super excited about the new Fallout. I loved the first two and picked up tactics here. Heard its not as good as the originals but I still love the setting and will give it a big try...

There are quite a few games I'd like to see sequels
Tomb Raider: Angel of Darkness
This game may had bad controls and quite a few bugs (and compatibility problems with my WinXP machine even if it works flawlessly with my Vista laptop), but it was one of the best Tomb Raider storyline yet from Eidos (not Crystal Dynamics). Pieter Van Eckhart became my favorite Tomb Raider villain and this game introduced quite a few interesting concept. But, it ends with a cliffhanger and I'd REALLY love to see how it ends.
Bioforge
This game is another Origin masterpiece. It has almost everything right, except for that anti-climax ending when the Player escapes Daedalus on a ship. The story was great and well written, but way too many questions were unanswered, thanks to the planned sequel that never happened. Where will the main character go, since he doesn't consider himself human anymore? Will he join the Phyxx in an attempt to rebuild their civilization? What will happen to Dr. Esher? What Mastaba' up to since Daedalus is destroyed? May we finally get that sequel?
Call of Cthulhu: Dark Corners of the Earth
It can't really have a sequel since the main character died, but I'd love to see more "Call of Cthulhu" games with this game engine (tweaked, of course). They created such a chilling atmosphere with the first game.
These are those I can remember on the top of my head.

For sure it would be nice if another MechWarrior would be released... Unfortunately it seems that it is not in Microsoft's plan to do so.
Also proper sequel of System Shock 2 would be nice. I mean no offense - BioShock was a good game but gamers expected so much more from it. It's good but it ain't System Shock 2 descendant.

I would love to have a new installment of the Legacy of Kain series, specially as the history is left really far away from a definite end.

I hate when there is a great game that ends with cliffhanger and there is no sequel in sight. So I would love to see sequel of any of those:
Crusader No Remorse/No Regret (I wonder how the sequel would be named)
Freespace
XIII (XIII presents the most cruel cliffhanger ever. The game practically ends in the middle of a dialog )
There would be more of them but these three series really haunt me in my dreams. I NEED to know how their stories end.

Advent Rising - The game may not have been all that successful, but the story was amazing and it was originally planned as a trilogy. The ending of the game was one of the worst cliffhangers ever (on par with XIII).
No One Lives Forever - The first two had some of the best spy humor this side of Austin Powers and there is so much more that they could have done with the title.
Freedom Force - Another game that was planned as a trilogy that never happened. At least we got two of the three games out of this one.
X-Com - I still don't understand why they stopped making games in this series. After Infogrames bought out Microprose they really dropped the ball with this one.
KotOR 3 - Yes, I know its been mentioned and I know about the MMO. The MMO is most definitely not KotOR 3. In fact, its not KotOR at all, its just The Old Republic. If I had the least bit of interest in MMOs, I might get excited about this, but since I feel that MMOs suck as a general rule, this is nothing but a disappointment for me. I want an actual single-player KotOR 3 that finally finishes the story they started in the first two games.
Vampire: The Masqurade - Bloodlines - This is the one that I am certain will never happen, but I wish for it anyway. White Wolf canceled the Masquerade line of games, started the Requiem line, then merged with CCP (of Eve Online fame) and are now working on a World of Darkness MMO. See above for my feelings on MMOs.

Starlancer 2.
It was one of the greatest most immersive games of all time, and freelancer was just...good, but not what made starlancer great. What made starlancer great was the whole feeling that you were part of something much greater.
Freelancer only scratched the surface of that.

Probably "No Chance"... :)
Karl

Yeah, I know. I'll have to develop it by myself... :) One the other hand I thought the same about Fallout 3, Golden Axe and others... I guess there's always hope. Perhaps only fool's one this time but it's all I have

The working title of third game was supposed to be "No Mercy", but unfortunately Tony Zurovec left the devteam and the game was canceled...

I was hoping for a Dungeon Keeper 3, like someone above said. While I didn't like 2 as much as the first one, I still wanted to be my evil keeping self. I still play Dungeon Keeper regularly, especially against my father on a local network.

No Mercy? Now that you mentioned it I do recall that name from one of the posters included in game's box. There was even boxcover if I remember correctly. They probably had the game almost done and then canceled it. That's even more SAD. Stupid memory, it makes me feel blue :)
Edit: Ok, I checked it. It wasn't boxart for third game, it was boxart for third movie (fictional, movie in the game world). My memory tricked me again. My bad.