My right knee was suffering Friday and Saturday, so I spent quite a bit of time googling to figure out what might have caused it and what I might do about it. In my googling I came across
This is by far the most informative, best written, clearest, most complete (insert many more plus-words here) site I have managed to find about leg muscles in general and their impact on knees in particular. There are explanations, strengthening exercises, stretches, programs, diagrams, words, beginners, intermediate and advanced sections.
Just thought I'd pass the link on in case anyone else wants to know more about their legs and knees.