Hi there,
I mostly wrote this because asphaltcowboy wanted to know, but some other people might as well learn along with him 
This is using 3Ds Max 5. You can download the beginning and finished files here (.zip)
IK Limb Solver is an extremely useful feature to use when making animations. They help to simulate realistic joint movement, usually for arms and legs, but if needed they would work for fingers, toes… anything really. The method I’ll use works best with arm movements, for some reason it doesn’t seem to work too well for leg movement, you would use one IK solver instead of two in that instance.
Setup
You have your beautiful model, in this case Master Chief from the video game Halo, and you have him all textured. You’ve added bones to make his skeleton for easy animation, but for some reason it doesn’t look realistic. First, select the model and right click in your viewport and goes to “Freeze selection.” This will make it tons easier to select the bones. This is the point in which the “beginning.max” is at, although it has the leg IK limb solvers attached.
Start With IK Solvers
Select the Chief’s upper left arm (as shown in the picture above)
With the upperarm selected, go to Animation> IK Solvers> IK Limb Solver, as shown in picture 2. You will notice there is now dotted line from the top of the upper arm to your cursor. Bring your mouse down to the upperarm/elbow joint.
The left elbow should flash white momentarily. You’ll notice a “cross” going through the elbow/upperarm joint. You have your first IK limb solver
Select the elbow now, and go to Animation>IK Solvers>Ik Limb Solver once again. Again, you get the dashed line, except this time you’re going to click the joint between elbow, and the left forearm (see picture above).
Easy enough, wasn’t it?
You will notice you can now move the Master Chief’s arm around with realistic joint movements. You’ll notice in the .zip theres a “finished.max.” I just re-did the steps above for the right arm, and now you can have all your animating fun. :cons:
I’m relatively new to character animation myself, and this is my first ever tutorial, so I apologize for any mistakes or bad advice I may have provided here, but thus far it has worked for me I’ll field any questions, although I doubt there will be many interested souls. You’ll notice the bones are already attached to the model, although there might be some loose vertices hether and nether. I’ll make a bones tutorial, another day. Its a whole new, much worse, monster to tackle.