Instead of looking to own yet another electronic device, why don't you find some modest computer hardware and setup a headless Linux server using something like Gentoo or Debian?

Use it as your own personal online file store, web server, mail server, media server, or anything else.

If you expose it to the outside world, you can even get to it remotely from anywhere in the world.

Especially if you use purely SSH to interact with the machine and don't even bother installing Xorg or another X server, it'll be an extremely lightweight way to get things done anywhere in the world.

You'll also get to experiment with means to secure your box from outside zombie attackers.

That said, if you are looking to spend more money, you can always look into digital photography. Within the last few years, a new breed of digital cameras have emerged that feature DSLR-sized imaging sensors (and image quality) in smaller bodies that still feature interchangeable lenses. Panasonic and Olympus pioneered this new market segment with their Micro Four Thirds system, but recently Sony and Samsung have been making waves with their NEX and NX systems respectively. If you truly buy into photography as a hobby, you'll always have a new gadget to purchase, as lenses can be an endless love affair. (The Micro Four Thirds lens line-up is fairly large now).

But... maybe you should try to budget before jumping in. Don't go broke now.

Personally, I now have a Panasonic GH1 with four lenses:
- Lumix G Vario 14-45mm f/3.5-5.6
- Lumix G Vario 45-200mm f/4.0-5.6
- Lumix G 20mm f/1.7
- Canon FD 50mm f/1.4

I would love to buy more lenses (I'm looking at you Panasonic 7-14mm f/4.0), but I really shouldn't afford to. And perhaps you shouldn't either... (just go have fun building your own inexpensive Linux server as I suggested earlier - much safer option)