In the comments for why balance patterns helen left a
link about removing a fish eye dart from the rear of pants that I thought was a good, clean, demo on a rather complicated pattern alteration. On this same web site there are a lot of other little demos. I didn't find any that were quite so well explained but there were some interesting ones anyway, many of which explain a "Full Bust Alteration" . Regrettably this is not something I have trouble with but its good info for doing other people's clothes.
The next one I want to mention is IPCA which I found through FI's links. This web site which sells patterns made by independent seamstresses is mostly patterns for the older, home sewing, crowd but it is an interesting idea. It is a collection of small pattern companies with reasonably regulated pattern standards. One of the pattern makers is Coni Crowford. I once went to one of her seminars here in Portland. I was quite fun. I must say I didn't wind up learning much I didn't already know but it would be a great expose on pattern drafting for anybody wanting a leg up on their hobby.
There is good book on how to make dress shirts by David Coffin. It is also the only book on dress shirts that I can find. It contains a lot of good info but is terribly organized. If you happen to want to sit down and try making a shirt you will find your self flipping back and forth through the index and a variety of book marks trying to get from step to step. But I also found a video that how to copy a finished shirt pattern which I think is a good intro to copying garments but I don't agree with all of it. I am much more thorough about truing my patterns. I also use my front pattern to make my back pattern and then compare it to the shirt. On cheap shirts there is no guarantee that the pattern was accurate to begin with and copying can make things very distorted. I think the best shirts to copy are expensive checked shirts. The checks give you a built in grid for checking your seams. For another good intro to copying clothing check out this book which also has its own issues. I would recommend checking it out at the library because once you see how its done you will probably never need to crack the cover again.