offers a limited free service, which I recommend.
You can also find a more thorough comparison of providers, including those offering free tiers here: http://socialcompare.com/en/comp...
Keep in mind that you can leverage free services and their limited monthly queries by wisely choosing your TTLs: Set them as high as you're willing to tolerate, particularly for records which change most in-frequently, such as MX records.Update:
I now use http://www.namecheap.com
more than zerigo.Update 2:
Zerigo has discontinued their free DNS offering.