I know the dude who runs http://everydns.com – they allow axfr’s which is convenient. Their web interface is good. I got sick and tired of updating BIND serials man moons ago.

Having AXFR authority is supremely convenient when you need to do massive updates via script or something, that way you can avoid using the web interface if you move like infinity domains around.

Hope that helps.

I use dnsmadeeasy.com

Um, http://www.opendns.com/