Anything I can do with an eMac G4?

Upgrade the Hard Drive, Max out the RAM, and make it an iTunes server.

use it as a dedicated word processor? :)

Use it as a side computer or keep it the way it is in case you want to teach someone how to use it? That way if they mess it up, it's not too big of a deal.

What version of OS X does it have. Upgrade that. I would recommend going to at least Tiger (10.4) as some apps still support it but if it can run leopard (10.5) fine go to that. You can't go any higher since it's PPC. To find OS X's version go to Apple>About This Mac if you already knew that sorry but you just seem like you don't know much about Mac's.

I would recommend running Synergy on it. It will allow you to do the following:

"Synergy is Free and Open Source Software that lets you easily share your mouse and keyboard between multiple computers, where each computer has its own display. No special hardware is required, all you need is a local area network. Synergy is supported on Windows, Mac OS X and Linux. Redirecting the mouse and keyboard is as simple as moving the mouse off the edge of your screen. Synergy is released under the GNU Public License (GPL)." - synergy-foss.org

Give me the computer because I collect old computers

i have an old powermac g5, 2ghz dual core, 512mb of ram, 9800 gpu, 250gb hard drive still pretty awesome for general purpose, minus the annoyance of powerpc being barely supported.