I'm guessing when you say "modern", you mean "military". Far Cry, for example, is a modern shooter with real weapons and human targets. It's just really unrealistic.
Realistic military shooters:
- Operation Flashpoint, VBS (for the truly hardcore), Armed Assault, "Gen 2 Game", "Operation Flashpoint 2"
- Rainbow Six series and Ghost Recon series
- SWAT series
- America's Army
- Insurgency for Half-Life 2
- Battlefield 2 Realism and Point of Existence for Battlefield 2
- DC Realism for Desert Combat
Non-realistic military shooters:
- Desert Combat for Battlefield 1942
- Battlefield 2
- Joint Operations and Delta Force: Black Hawk Down series
- Soldier of Fortune series
- Full Spectrum Warrior
- Close Combat: First to Fight
- Counter-Strike series
Realistic WWII Shooters:
- Red Orchestra
- Forgotten Hope series for Battlefield 1942 and Battlefield 2
- Day of Defeat series
So there are plenty out there. What there HASN'T been in a while is a game like Call of Duty 4 - an unrealistic military shooter with the focus on a cinematic, single-player storyline. All of the ones we've had were either WWII, Vietnam (like Men of Valor), semi-Sci-Fi (like Far Cry or FEAR), or Sci-Fi (like Halo and Quake 4). It'll be interesting to see how this goes.