My question probably doesn't have a good answer, but it's worth a shot. I am going to be out of the country in a couple months and I will not have access to my guitar for over three weeks. I have recently been trying to work daily with my picking and fingering speed and I'm worried about any progress I've made getting lost. I will take a theory book with me so that I can at least do something guitar related while I am gone, but is there some sort of physical exercise I can do though, particularly with my picking hand, so as to build up the speed? (Unfortunately my masturbation technique comes from the elbow rather than the wrist.) Seriously, though any suggestions?

Don't stress. You aren't going to backslide much in three weeks. You are going to run into spans of time throughout your life where you just can't play(I've gone 2 or 3 years before). It is inevitable. It's a lot easier to get to a previously achieved level of playing than it is to get to one never acheived. You will be fine.

Save your stress over retaining technique for when you are in a band and have to go away and you have a show as soon as you get back(been there).

As you said, if you absolutely must do something music related, focus on memorizing the fretboard and learning the cycle of fifths or something.

Yeah, I'm probably worrying too much. Regarding memorizing the fretboard, circle of fifths, etc. is there a good book you would recommend? I was also thinking maybe of starting sight reading and/or ear training as well. Again, won't have a guitar to actually put any of it into practice, nor will I have a computer. But I will have my mp3 player as well as any books I buy. Ideally though, I'd like something I can do while sitting on the beach, in other words, nothing that requires too much effort.

i dont know if this is any good but i found this using google

http://www.amazon.com/Music-Theory-Guit ... 063406651X

looks promising

As far as books, I'm pretty out of the loop. I did that in college(I went for classical guitar) and most of those books are either textbooks, or out of print.

I know it sounds lame, but the single most important thing you can do away from your instrument to train your ear is sight-singing. It teaches both ear training and sight reading. There are lots of books for sight singing which are just comprised of small excerpts of music which are used for solfege.

http://en.wikipedia.org/wiki/Solfege

To me ear training is far more important than theory and the only way to truly train your ear is knowing how to sing from the page with no help from any instrument. This is why when you attend a music conservatory the first class you are enrolled in is sight-singing.

http://www.singers.com/instructional/sightsinging.html