Main Battle Tank - Merkava MBT
http://www.fprado.com/armorsite/Mekava.htm
Unique among the main battle tanks of the world, the Merkava design features a front-mounted engine and battery, room inside for several full armed soldiers in addition to the crew and a rear access hatch allowing for the quick evacuation of crews and injured soldiers. Enemy fire directly striking the front of the tank, the most likely point of attack, is absorbed by the mass of the engine block, protecting the crew. The engine pack is easily replaced.
This tank has always impressed me. The unique capability of carrying a couple of fully armed soldiers inside I always thought was pretty cool. I realize that the APC is a lot cheaper than a tank and can be produced in greater quantities, but personally I would feel safer being transported to the battlefield in a tank than an APC. Besides, I don't think a tank crew would mind having a couple of dedicated dismounts in support of their vehicle. Interesting concept -- I'm a bit surprised nobody else has tried something similiar.
Checking out the Mk-4, I'm very impressed with the listed capabilities. The 120 mm gun with the capability to fire LAHAT 120mm missiles, an internal 60mm mortar, 3 x 7.62mm MG -- not to mention all the protective systems, laser warning system and more!! I would sure hate to be fighting against a unit with those.