I thought that it would be nice if each one of you would tell us somthing that exists in max n we didn't knew about it, somthing that will make our work easier.
When you draw a spline you can press I while drawing the line to switch to interactive mode.
To dynamicly work with modifiers you can drag and drop modifiers from one object to another. I.e. you have cube 1 and cube 2, cube 1 has meshSmooth on it, you can click and drag meshSmooth onto cube 2 and it will be copied there. You can hold down ctrl + drag will instace the modifier, shift+drag will move the modifier from one object to another.
In material editor you can rotate a shader by middle mouse button clicking and draging on it.
If you select a file from explorer and drag/drop it onto mat editor shader slot it will add it into diffuse channel. You can drag any texture maps from explorrer into any mat editor slots, with out having to go and click (channel/bitmap/brows for bitmap).
This one is a rather warning for max 7 users: did you know that if you instance a map in one mat two or more times, then click make unique button it will destroy the shader.
Reactor dynamics: when you are trying to simulate two objects which have to look like they are side by side and reactor gives warrning of object intersecting, put a push modifier with a small value of -0.05 to shrink the objects temporarily, after the simulation you can turn off the push modifier and have everything looking correctly and colliding.
Did you know that by default settings quasi monte carlo for primary bounce (Cool will render slower and more graynier image then if you turn up global QMC sampler subdivision to 4 (cleaner and faster). And making quasi for secondary bounce (exterrior) will make it render even faster, and even faster with global subdivisions to 4.
Did you know that 3ds max maximum frame range in time slider is -10000 to 10000.
Particle flow is terrible with max collision objects, avoid using heavy instaced objects colliding, this will result it horrible render times due to PF precalculations. Making PF cache to disk will make 3dmax files aroun 600 mb and still wont be anywhere near as helpful as one would want.
Did you know that while working in editable poly mode ctrl + I (invert selection) does not work, but it works fine if you go edit/selection invert.
Did you know that MeshSmooth will crash max at level 7 subdivision and TurboSmooth will still render all though at 2.5 gb of ram, but it will be fast and efficient. So since turbo smooth showed up I dont use meshsmooth that often. (test done on a primitive sphere renderer on mental ray)
Did you know that procedural textures in vrayDisplacement Mod will render much slower then baked textures.
Attaching multiple heavy objects in 3ds max via editable mesh/poly will perform a memory leak which will force max to jump the memory to maximum then crash. (test is done by cloning 100 (100x100) spheres and attaching them all in one batch. While if you attach them one by one your memory will grow exponentially, but you will be able to attache an nth number of them then save, close max open max and continue. (maya can do this attachement with memory under 900mb)
Vray does not motion blur any light types, so if you have heavy motion in your scene which depends on precision lighting, do not use lights, rather use gi emmited objects.
Vray does not motion blur lights thus does not motion blur any volumetric effects corelated to lights. Solution is to use camera multipass effect with duration corresponding to you motion blur to render a separate pass.
Vray has hard time motion bluring particles which spawn and die between frames. If the blur is not too heavy you can use 2d effects motion blur, works well.
Vray cannot motion blur Fluids like realFlow mesh or Glu3d, again 2d blur would work for some cases.
When rendering single objects or passes like shadows use region to cut down on antialiasing of black unnesesserry space. Just make sure your object does not exit the region on a certain frame.