What version of openSUSE are you using?

You can get OggConvert Packages for openSUSE 10.3 and 11.0 through the openSUSE Build Service.

If your using openSuSE 11.1 just do a google search for "oggconvert" then click on the first result and you should be at the OggConvert Homepage. From there find the .tar.gz source package and download it. It's written in Python so you don't have to compile and install it. You can just extract the files, chmod oggconvert, and to exec just type "python oggconvert"

You could get an RPM from h31's repo at
http://download.opensuse.org/repositories/home:/h31/

It is available in the noarch directory.