No emails listed in the WHOIS at all? Try webmaster@domain, postmaster@domain, and a few variations of those. Or dig into one of the "whois archive" web sites,

No emails listed in the WHOIS at all? Try webmaster@domain, postmaster@domain, and a few variations of those. Or dig into one of the "whois archive" web sites, maybe you'll find an earlier WHOIS record with owner info.