http://en.wikipedia.org/wiki/Bisphosphonate#Adverse_effects

I'd be very curious to hear about the side effects of using these medications in space. Grandma had plenty of difficulty using them here on earth...

And the average age of those 700,000 license holders? Anybody?

I hold an extra class license, which I don't really use, and my impression was that the average age was around 65. If you want to tune in and chat with other oldsters about medical problems... then amateur radio is for you! Though some will treat you as a lower class of operator for not being a "brass pounder" (i.e. someone proficient in morse code). And you might feel unwelcome if you're LGBT; they're, um, a little on the conservative side.

On the other hand, the tech stuff is pretty cool, and if you're comfortable with algebra, trig, complex numbers, and memorizing some stuff, a good geek should be able to test all the way to extra class on the first try with some studying. I did, and my math skills were quite rusty. It just took a little practice.

And building radios is actually quite fun. I recommend:
http://www.elecraft.com/k2_page.htm
from
http://www.elecraft.com/
which is a nice blend of "the old days" and "somewhat modern stuff". Fancier radios are built by plugging the boards in, just like PC's. This one gets soldered together one part at a time.

There are also lots of plans for building radios from scratch that are drifting around the net. From a modern day perspective, it's fascinating how much you can do with a handful of discrete components.

So, in conclusion, if you're interested, amateur radio is worth checking out, just beware of the subtle demographic issues that might present themselves.

The Kindle DX is my favorite for simple documents I read through linearly, one page at a time. It's light and runs a week or two on a charge with the wireless switched off. The iPad is much better (and significantly faster) for programming books, and technical papers, but is quite a bit heavier and generally needs at least daily recharging.

For scientific papers, I'd either go with an iPad, or wait a little while to see what Amazon has planned for the fall.