Attached is the file cthumb.tar.gz which has the ebuild-file, the Changelog and the digest-file (dunno if that's needed) of cthumb version 4.2. I've used it before succesfully before I got a PHP-file that made it automatically. It creates very decent image galleries such as like http://www.lugwv.be/meetings/page.shtml. No patches needed. Its the first cthumb-ebuild for Gentoo (i.e. there is no older version, this is no upgrade). I suggest to put it into app-misc like bbgallery (a perlscript with the same features).
Created attachment 3682 [details] cthumb-4.2.ebuild
Now in portage. Open a bug if you have any problems, installed smoothly and appears to be working.