I have recently released the MH-X Silent Hawk with working landing gear on GTA4-Mods.com
So, apart from the Cougar MRAP and a few more V vehicles.... What else is there? Well... Some Black Hawks again.
UH-60Q MedEvac with medical equipment and external fuel tanks
MH-60 "Nightstalkers". Includes many extras, including: MH-60L FLIR, MH-60K FLIR, external fuel tanks, external refueling boom. So you have a lot of combination choices.