I've been working on getting all my programs in Redhat 9 to work (setting up Mutt, fetchmail, etc), and I've noticed that often when I try to install programs (especially RPM's), I get messages saying there's a file that is missing. For instance, I tried to install the newest version of GAIM, and got this:
libgtkspell.so.0 is needed by gaim-0.68-1rh9
am I missing something? they always seem to be .so.0 files, if that helps. Help with just this AIM issue would be nice- from there I can hopefully figure it out by myself.

so means "shared object" what basically this interprets to is something that many programs will use/have and require to run. It's a 'module' thing, all applications don't necessarily come with all required files, they expect some to already be installed, or installed along with them. To resolve these 'dependencies' it's usually suggested to get something like apt with Synaptic from:
www.freshrpms.net and set those up to download/install the applications you are looking for. Otherwise, you can run into cyclic dependencies which is horrible, and dependencies for your dependencies which sucks just as bad. If you don't want to go that route, you can instead head over to something like www.rpmfind.net and search for "libgtkspell" to find which RPM contains that file. Then search your install CD(s) to find that RPM and install it.

HTH

Cool

This is refered to as "depency hell"