Italeri does a 1/24 scale Willys Jeep and a Fire Jeep (same kit with a sprue of fire fighting fittings).
Tamiya does some 1/25 scale armor like the Tiger I, Centurion, T-34, Panther, and Jagdpanther, but many are long out of production. I've got the Tiger I, and it is not a bad kit.
Academy released copies of several of the Tamiya kits. I've got the Jagdpanther and had fun building it.
AMT released the old MPC Hogan's Heroes Jeep about a year ago. I do not recall if it was 1/24 or 1/25 off hand.
ITC (Ideal Toy Company) made a neat kit of the T-92 US Airborne tank in 1/24 scale. Another really cool kit of a tank the US Army only made two of. This one is long out of production.
There are some rather expensive Japanese remote control armor kits in 1/24 scale. They fire airsoft BBs and are made by Mauri or something like that.