Sequels I'd like to see:
- Republic Commando 2
- Republic Commando 3: Empire Commando (Seriously, who wouldn't like to play a stormtrooper?)
- KOTOR 3 (I look forward to the MMO as well, but KOTOR 3 would be great... if they allow themselves time and budget to actually finish it this time.)
- SWAT 5 (with the relative realism and good character models of SWAT 3, and the more user-friendly approach of SWAT 4, and with a nice plot.)
- Half-Life 2: Episode 3 (or are we talking about sequels that might actually happen?)
- Mass Effect spinoffs; yes, I want Mass Effect 3 with Shepard, but imagine these:
-- Mass Effect: C-SEC (Garrus before joining up with Shepard, or possibly Chellick, in an investigative RPG and shooter)
-- Mass Effect: Humanity's Ascent (Space and ground strategy game set during humanity's discovery of the mass relays, up to and including the Turian wars.)
-- Mass Effect: Arcangel (Garrus' adventures on Omega)
-- Mass Effect: Fall of the Protheans (The final days of the Protheans)
-- Mass Effect: Shadow Broker (Commodity trading and espionage simulator, possibly with first- or third-person elements)
-- Mass Effect: Alliance Marine (First-person shooter, from the Rachni Wars, through the Krogan Rebellion, to a last stand at Eden Prime.)
- Ultimate Peggle: The Revenge Of Peggle Extreme (OK, maybe not.)
- Monkey Island (A first- or third-person modern-style RPG)
- A better Mafia 2
- Saints Row 3 (or at least those DLC packs being released for SR2)
...and a few others I can't think of right now. There are a lot of games I've enjoyed enough to want sequels to... ;-)