You've gotten a lot of great feedback already, but I'd like to add my $0.02 to the pile. My comments will be a little more general in nature.
I would like to see a book that covered gas, stick, and TIG welding because those are the processes that I would use most. I'm learning on gas now, but want to use stick for the thicker metals and for structural stuff that I will build around the farm. I will use TIG later if I produce any metalwork that needs to have clean/pretty welds such as furniture, etc.
I think that a book that explains the *why*, the principles behind a process/technique would be far superior to a book just showing how to do something. I've never learned (really learned) how to do something from a recipe or a list of steps. In my experience learning to duplicate a set of steps is worthless because when faced with a new situation or problem to solve, the recipe doesn't fit and you don't have the skills to adapt to the situation or problem.
Also, I think that a DVD would be an excellent idea. I have some DVDs from WeldingVideos.com and they are fantastic. To see the welds being made close-up and have the action stop and various things pointed out during the process is very very helpful. And, because it's on DVD, I can go right to a particular section and watch it over and over and over. This has the effect of reinforcing what I've read in other books and shows me what I should/will be seeing when I go out to the barn and fire up my torch. Then I can go back inside and review and compare what I saw to what the video showed, make adjustments and go out and have another successful practice session.
I hope this helps identify some of my needs and some things that may be beneficial to others.
rvb