Ok, I know 3 modeling tools: 3dsmax/GMax, Milkshape/MisfitModel and Quake2Modeler. Of these, I worked mostly in the latter. In my opinion its brilliant interface features making it extremely comfortable to use, much easier and ergonomic than the former two.

:!: The question is: does anybody know if Q2Modeler's interface is copied after some other well-known tool I don't know of? (like LightWave). The interface features (as well as the horde of bugs, sadly) are listed below.

:idea: Why am I asking this question: I plan to create a built-in 3d editor for my engine, and plan to take the Q2Modeller's interface as my shining model (adding the skeletal animation, of course).

You can the tool itself here:
jDoom Modelyard -> MD2 and DED creation tricks -> Tools (sorry, the site uses frames, impossible to link directly to the right part). It ran for me under Win9x, WinXP and wine (Linux Mandrake 9.0).

What I wrote on the subject three years ago:
Important keys:
Shift: pan views (synchronously, and it's great!) or rotate 3d-view by left mouse button, or zoom views by right mouse button.
Alt: substractive selection mode (else additive)

Features:
1. 3d view is always aimed at point, defined by center position of 2d views, and rotates around this point. Great for aiming at part of the model, and rotating around it!
2. To copy part of one model to another model, you may copy-load-paste (unfortunately, Q2Modeler not uses Windows clipboard)
3. There is a great thing: support of reference models (good for synchronising multipart models), but it works properly only if all numbers, names and total number of frames in both models are equal. And often crashes at loading of reference model - be careful, save often (.AQM, of course, to not accumulate quantization distortions)

Quake2Modeller v0.91
- can properly display skins with any palette, but cannot play model animation.
Quake2Modeller v0.90
- cannot properly display skins with palette other than one of Quake2, but can play model animation (on any speed and with inter-frame interpolation)

Severe bugs list:
1. (Nasty) After you rotated 3d-view, each first attempt to move vertices forces them to "jump" in a random direction. Watch out, and hold your fingers over Ctrl-Z keys (undo). Second attempt always works well.
2. (Dangerous) Often crashes at deleting vertices (especially if 3d view is set to "textured")
3. (Dangerous) Sometimes crashes at switching 3d-view to "Textured", and often crashes at loading model if 3d view is set to "textured".
4. (Dangerous) in v0.91, attempt to play animation writes some frames over other ones - DON'T TRY USING IT! Use only in v0.90.
5. (Dangerous) in v0.91, loading reference model causes frame #0 to be replaced with some other frame.
6. (Annoying) At exporting MD2, you each time must select all skins that model uses.
7. (Disadvantage) AQM files (native Q2Modeller's format, that not adds quantization errors, and MUST be used for saving the work-in-progress) from v0.90 and v.091 are not compatible...

Warnings:
1. Make sure, that "base path" in "directories" settings is set to folder, containing model that you currently editing (to leave skin path empty), or jDoom will not find skins.
2. option "weld vertices" don't makes one vertex from them, and don't deletes faces using them! It just sets same coordinates for them - so be careful, don't spawn "triple" vertices and zero-size triangles, that will just unnecessarily strain the game engine