Two great tutorials form the web site of Mike Brown.
A nice simple, concise and clear walk tutorial. Added to the Walks and Runs resource section.
Ahhh that pesky old Gimbal lock. Its mysterious, strangely seems to affect some animators more than others, and can be a real pain in the but. Your best defence is to understand it as best you can so you can recognise it when it happens and rethink what your doing. This tutorial is a nice clear explanation, and I'm adding it to the Maya Tutorials resource section.