The Android tablet space that is starting to heat up is all running after Apple's iPad at the moment. It's got a nice form factor and a nice screen, but it's entirely unsuitable for a whole set of applications that I care about for one simple reason:
LCDs give off blue light.
Blue light is really the enemy of both sleep and dark. I mostly care about the dark part, because my interest is for Astronomy. It takes at least 20 minutes for your eyes to really dark adapt when you go outside. If you want to see other Galaxies from your back yard, dark adaption is really important. We call them "faint fuzzies" for a reason. Last month at our astronomy party someone brought an iPad with some astronomy application to let them know what to look at with their telescope. After 30 minutes of it blinding them, the finally turned it off and started asking some of the rest of the folks there what they should be looking at, and where to find it.
But, an eink tablet would be great. You could use just enough red light to see what's going on, and be able to zoom in to your charts. There are 2 things that come close right now, the nook and the kindle, but neither would work without a lot of effort. To do your own apps on the nook you have to hack the thing, and you've still got this pesky lcd you'd need to put a filter over. The kindle is a physically better device for this, but it's not android, so it's another sdk to learn, and they have all manner of restrictions because the user doesn't pay for their data usage. As far as I can tell it would be too restrictive for this.
The ideal device would be something like the kindle dx, have a gps, and be based on Android. This device doesn't exist, but heres to hoping that someone makes one eventually.