LAN Messenger - LAN Messenger is a decentralized UDP IM-style chat client which supports usernames...
HostsMan - HostsMan is a freeware hosts file manager and editor. Built-in hosts file updater
Softros LAN messenger - LAN messenger for an internal office chat for home or business users. It does not require a server and is very easy to install and use. It supports personal chats, group chats, message brodcasting, files transfer and remote desktop access.
Gas Mask - Gas Mask is simple hosts file manager for Mac OS X.
Bopup IM Suite - Organize secure messaging system and communicate instantly via self-hosted IM server.
SwitchHosts - Free and open source hosts management & switching app