Yahoo! recently lowered the price for all domain registrations to $9.95/year. It looks like the idea is to bring in more domain registrations and hook people on the other Small Business servics. I've not used any of these, but have heard that some (especially the simple web hosting setups) are getting good reviews.
For now I'm sticking with pairNIC which is slightly more expensive (best price is $13/year for 5 year renewal). I've found the service for pairNIC to be excellent so far.