Sins of a Solar Empire Rebellion
Elemental: Fallen Enchantress
XCOM: Enemy Unknown (fairly new game, but I'm liking it a lot)
Battle for Middle Earth 1/2
I also saw someone mention Mount & Blade Warband, which is more of an Action-RPG with slices of strategy (you play it in 1st/3rd person for starters). There's also some awesome mods for it out there, but not all of them work in MP.
"In order to maintain a tolerant society, the society must be intolerant of intolerance." Paradox of tolerance
The greatest real time strategy game to date, is Supcom FA. It is very difficult to learn and requires the best computers, even today 5 years after the initial release.(today the average gaming pc can actually run it, unlike when it was released) These two barriers have made it unaccessible for many gamers. Those of us who were lucky enough to experience it and stuck around long enough to learn it are now addicted for life. Here are some examples of the gameplay(warning: this may blow your mind, shit like this is not made and advertised by game publishers because it is way beyond them) youtube.com
watch?v=garcX07-e4w
watch?v=Qnn-qTByUKI
watch?v=UbRvci4DuMQ