For making a level in Maya out of MDL's, Ventilator's Obj_Splitter is free, stable and does the job very well.
I just put it online for you to download.
http://www.milkycat.com/cobweb/obj_splitter/I've used it literally thousands of times. It works by exporting your level from maya as a multiple-object obj file. Then it converts each object in the obj file into a MDL. Next, a wmp is built so that all the MDL's are in the same position as the Maya level. And all the attributes you set for the obj in Maya (stashed within its object name) are assigned. It exports the wmp, builds a wmb and even runs it for you. It's not as pretty looking as MayaTo3DGS, it's a little tricky to set up at first, but it's a workhorse: very effective and very stable. For the time being I think it's probably the most practical and effective solution for MDL based level design-- and you can also use it with other 3D applications that support obj export and a little bit of scripting!
If its not level design in Maya you want, but instead animation, use ActorX tool for bones and vertex animation, or ventilator's older maya exporter for vertex animation. For vertex animaton I find Ventilator's Maya exporter to be easier to use, with its automatic cycle naming system.
