TShock is a server modification based upon High6's mod API that allows for basic server administration commands.
Constant builds: http://ci.shankshock.com/
If you'd like to help out, the best thing you can do is to fork this repository, add changes, and request a pull back in. Try to make your changes on the latest code possible so that merging doesn't take ages, but other than that we accept any improvements or changes.
We communicate on the ShankShock Temspeak server whilst programming.
IP: ts3.shankshock.com
Port: 9987
We love IRC (although a little less than Teamspeak). If you need support, or just want to hang around, feel free to join.
IP: irc.shankshock.com
Channel: #terraria
If you're a project contributor and you want to be able to push updates, talk to nicatronTg (shank@shankshock.com) about getting FTP access.