GoDaddy $1.99 domain names
This is probably the cheapest domain non-info deal I’ve come across:
$1.99 domain name registrations, transfers and renewals with no quantity limit.
Condition: buying one new, non-domain product or service.
So far I’ve found two registrars offering this (practically the same) deal (GoDaddy and SSL Catacomb Networking):
You do not need a coupon to get this deal with either company.