WhoisThisDomain - Domain name lookup tool that allows you to get information about domain registration from WHOIS server.
ServerSuit - ServerSuit is a browser based program that enables remote Linux administration, monitoring, website hosting, and server setup automation.
Whoisology - Connected database of whois records and whois history
AppZero - AppZero is a monitoring and migration tool that allows users to keep track of different applications and servers in both simple and complex IT environments.
JSON WHOIS API - Parsed domain WHOIS data from any WHOIS server via RESTful API with metered pay as you pricing.
CULA - A webmonitoring solution for beginners and pros.