CGUpdater

For newer versions of minecraft (1.8 +) this mod is included in the cgutils mod 

The purpose of this mod is to download files such as config or minetweaker scripts from a web server. This means files can be updated without having to update the modpack. This mod can be especially useful if you own a server maintained by multiple people who need a quick and easy way to push updates to the config or recipes without forcing users to update the modpack or even leave the server.

Groups of files can be specified in the config so that they are downloaded with a single command.

You can also use the /directupdate command to download files individually.

Files can only be downloaded by server admin.

Files of the same name will be overwritten when downloaded.

You can get more information on how to use this mod on the wiki

A working example of how to set up the web server files can be found here

The source code is on GitHub