I'm using whois.sc You can sign in as member and use all the nice features they offer, like domain watch, alerts, whenever someone registers a similar domain as yours and more.
I don't think I have developed IPWHois with the aim of domain service related functions. This is a simple IPWhois tool where you enter the IP address and the script will display results such as from which country the IP originates, which Town and the Service Provider. The tool was originally created with the aim of tracing the origin of e-mails, which is currently being used by a number of law enforcement agencies in investigations of crime.