Hostess

Hostess is a free software tool that will help you maintain your Hosts file. Unlike many HOSTS file utilities, Hostess is geared towards ad-blocking rather than IP address resolution.
Hostess stores your host entries in a database that is indexed to eliminate duplicates and make searching fast and easy. It also allows you to group these hosts for efficiency and ease of maintenance.
Messing with the HOSTS file is not for the inexperienced user. There is the possibility of undesirable and sometimes difficult to troubleshoot effects on your Internet and network connectivity.
The documentation included with Hostess gives only a basic overview of how the HOSTS file works. Better sources of such information can be found by doing a web search for "HOSTS file".
Hostess has been designed to make things easy for the experienced HOSTS jockey, someone that wants a fine degree of control over what goes into (and stays out of) their HOSTS file.