The InetVote system is infrastructure for voting on the Internet. It includes online registration (requiring access to credential data which must be arranged by the individual jurisdictions). Resistance to election fraud is as good as or better than existing manual systems. From this page you can run a demo of InetVote. It is available both via HTTP (port 80) and HTTPS (port 443).
Look for a discussion of weaknesses, in both InetVote and the present manual system, at the end of many of the pages.