In order.
MJ modular M4. This is the best 1:18 scale accessory ever made. Maybe Mola Rom's bearning heart fromtEmple of Doom will give it a run for its money once it is released but right now there isn't anythign even close. The fact this came from a small e-tailer instead of the big H is just mind blowing.
XD Bradley. Tons of detail. Tons of playability. Moving treads. Opening hatches. This toy is everything I wish a modern GI Joe tank could be.
PTE Tower. With the its simplicity and attention to detail (currogated roof and rope ladder) this thing harkens back to the golden age of ARAH GI Joe when mini playsets ruled the day.
PTE Blackhawk/F-18/Little Bird. I like all three of these for all the same reasons. They fill a huge void in the GI Joe line, add real world military equipment to my forces, and have just the right balance between playability and reaslistic features.
Honroable mention goes to the Galoob A-Team vehicles. The armored car specifically is afavorite of mine.
http://www.toymania.com/334archives/ateam/car.htmIf I could find any at a decent price I'd probably include some Action Force/Red Shadows vehciels here too.