No, the Revell-Monogram one is all there is in 1/25 scale. It comes in several variants like the Jurrassic Park Snagger, TOW (regular green and ProFinish camo), and 4-door (red and ProFinish in black). They have a basic non-military interior with no engine or real suspension detail.
Maitso (sp?) makes a 1/27 scale diecast one that is also packaged by Testors. Thick coat of paint cover most of the detail on these. Less detailed than the R-M ones.
In 1/35 scale, Tamiya recently released a new tool kit, but has no engine. Do not mistake it for their Hummer with M242 Bushmaster. That kit is a reboxed Italeri mold.
Academy makes four different HMMWV variants and are still fairly available.
Italeri makes about 7 different ones that are basically the same body and chassis. Revell of Germany also boxes two variants of the Italeri kit.
Esci (AMT/Ertl) made 3 or 4 different ones that were the worst of the lot.
CMK makes a resin engine insert for the HMMWV. It is not a full engine, just enough to make it look like there is an engine when the hood is built propped open.