What are some alternatives?
When comparing Ajax Domain Finder and Domainr, you can also consider the following products
Machiname - Machiname is domain name search tool that lets you enter keywords and it will look up domains availability for every combination
Nuage - Nuage provides domain naming services.
DomainHole - DomainHole has the tools to allow you to find a great domain name.
Agile Domain Search - Search great domain names for your website in seconds.
namegrep - Domain name search with regular expressions and curated sets
Lean Domain Search - Find a Great Domain Name w/ twitter handle availability