Detours Clone is a super fast way to edit your hosts file.
Detours Clone is a clone of Detours App by Jerod Santo - Jerod Santo. Except it's not Mac specific because it leverages the hosts file instead of OS API's.
If you are on a Mac, I'd use the real thing. If you are on Linux, you might give this a shot.
Essentially it maintains a chunk of your hosts file (think /etc/hosts) in a parseable fashion and gives you access to easily change it from a client app.
This app involves a client and a server, since on Linux the hosts file is protected we have to run our daemon with a privileged user. The client and server communicate via TCP sockets with JSON.
Currently there are three Python clients. One is an HTTP server, one is GTK, and one is Qt4. You can write a client in any language as long as it can talk on TCP sockets and has a JSON implementation.
Heck, if you are clever you can talk right to it:
jmhobbs@asuka:~$ telnet 127.0.0.1 8552
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
{"method":"list"}
{"pairs": [{"ip": "127.0.0.1", "host": "google.com"}, {"ip": "127.0.0.1", "host": "gmail.com"}], "response": "list"}Connection closed by foreign host.
jmhobbs@asuka:~$

Qt4 Client

GTK+ Client (In KDE)

HTTP Client (In Chrome)
Python is required for the server. Also, the python-daemon module is required (for now).
$ git clone git://github.com/jmhobbs/detours-clone $ cd detours-clone $ python setup.py install
MIT
Copyright (c) 2010 John Hobbs Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
John Hobbs (john@velvetcache.org)
You can download this project in either zip or tar formats.
You can also clone the project with Git by running:
$ git clone git://github.com/jmhobbs/detours-clone