Portage contains http://grammarian.homelinux.net/abakus/ as the URL for abakus, which doesn't connect. Through Scroogle I found this page which appears to be the new home of abakus: http://purinchu.net/abakus/
+ 29 Mar 2009; Patrick Lauer <patrick@gentoo.org> abakus-0.91.ebuild: + HOMEPAGE fix, closes #264052
Thanks