I'm running SuSE 9.0 and I'm trying to install the XMMS and volume plugins for Gkrellm. I pretty much the same overly long list of errors for each, but its actually a few hundred thousand characters more than will fit in this post.

I'm no expert, but that seems like rather a lot of errors for a simple plugin. Anybody know what the hell is wrong with it? Or perhaps where I can find an RPM?

well unfortunetly without errors its kinda hard to tell you whats wrong without actually knowing whats wrong ... and yes as you say there is alot of output that may be too much to post, but usually the relevance is in the last few lines, so maybe posting a partial message may lead to a resolvment ...

Alright, here's the first chunk of it.

cc -O2 -Wall -fPIC `pkg-config gtk+-2.0 --cflags` `xmms-config --cflags` -DPACKAGE="\"gkrellmms\"" -c -o gkrellmms.o gkrellmms.c
/bin/sh: line 1: pkg-config: command not found
/bin/sh: line 1: xmms-config: command not found
In file included from gkrellmms.h:24,
from gkrellmms.c:22:
/usr/include/gkrellm2/gkrellm.h:30:21: gtk/gtk.h: No such file or directory
In file included from gkrellmms.h:24,
from gkrellmms.c:22:
/usr/include/gkrellm2/gkrellm.h:191: error: parse error before "gfloat"
/usr/include/gkrellm2/gkrellm.h:194: error: parse error before '}' token
/usr/include/gkrellm2/gkrellm.h:212: error: parse error before "GdkFont"
/usr/include/gkrellm2/gkrellm.h:214: error: parse error before "privat"
/usr/include/gkrellm2/gkrellm.h:215: error: parse error before "effect"
/usr/include/gkrellm2/gkrellm.h:216: error: parse error before "internal"
/usr/include/gkrellm2/gkrellm.h:217: error: parse error before "flags"
/usr/include/gkrellm2/gkrellm.h:218: error: parse error before "color"

It goes on with a buttload more "/usr/include/gkrellm2/gkrellm.h:218: error: parse error before "x"" errors.

cc -O2 -Wall -fPIC `pkg-config gtk+-2.0 --cflags` `xmms-config --cflags` -DPACKAGE="\"gkrellmms\"" -c -o gkrellmms.o gkrellmms.c
/bin/sh: line 1: pkg-config: command not found
/bin/sh: line 1: xmms-config: command not found

judging by this you don't have your xmms-devel package installed, which i think is required to install plugins for xmms...
well obviously for this one cause it says stuff like not finding xmms-config which is in the devel package ...