Input Hive is a server client application. Clients can connect to the server by filling in it's IP adress and can then send keys to the server. The server can change what keys can be send per client.
For example:
You want to play Soccer Physics with your buddy, but the game is played on 1 pc. The controls for this game are A+D and ← and →. So you start up a Input Hive server and only allow the keys A and D to be "send" to the computer. Then you call your buddy on skype and start Screen sharing. Next your buddy starts up the Input Hive client and connects to your server. Now whenever your buddy can send the keys A and D to your computer and you can play the game together.