Too many to recall, but i'll try

Monkey Island
Indiana jones (adventures)
Day of the tentacle
Syndicate
X-Com
Carmageddon
X-wing vs Tie fighter

and so on...


I know that there is probably no chance to see sequels for the old lucasarts adventure (well, sam & max did make it, so hope dies last), but i really don't see why they don't make sequel to Syndicate and a proper sequel for X-com. They could even just make a remake of the original in 3D (but still isometric view), with the same game mechanic and new missions.

I miss Killer Instinct.

Grandia...

Oh yeah grandia ... The second one was really good! Grandia remake on PSP!

Well, there's a lot of factors for a Chrono series coming back, but mostly because all the people who worked on the original games are flung all over different companies now.  And the people who wrote the original script for the two games made their own studio...and then left that studio.

They should just work on getting just the original writers back (they're a pair I believe) and then they have all the people they need to make a Chrono game.  Just get Level-5 to do it and assign Yuji Horii, Akira Toriyama and Yasunori Mitsuda to the job.  There, you have 3 of the 5 big names from the original Chrono Trigger staff.  Plus Level-5 of Dragon Quest VIII fame.  If THAT can't get a new Chrono game done and done RIGHT, no one can.

Anyway, the series I want to see come back are:

Chrono, Suikoden games like the first 3, 2D Metroids.

Many other things, but they aren't series.

Driver.

Driver made GTA what it is. Obviously Driver didn't have guns, but I'm referring to a free-roaming driving game where you can steal cars and run from cops.

Toejam & Earl

I just remembered Golden Sun. I'd really like to see a console itteration, imagine the potential! Of course good old Starfox is in there as well, but now it's never going to happen because the fanbase bashed the Gamecube games so badly.

Hitman

I miss the double dragon franchise.
I wish the 2-D side- scrolling fighting games made a comeback.