I'm rewriting GSview (PostScript previewer based on Ghostscript) and I am currently working on the gtk+ version. The old version uses gtk+ 1.2 and the Aladdin Free Public Licence, while the rewritten version uses gtk+ 2 and the GPL. If you are familiar with gtk+ 2, and are willing to answer the occasional programming question, please send me email at gsview at ghostgum.com.au. I'll try to make sure I RTFM before sending questions.
If you are interested in trying an early version of the code, see cvs.ghostscript.com and look for the GSview tree. Suggestions for improvement to the old GSview, or the new rewrite are always appreciated.