CraftProxy is a reverse proxy, much like BungeeCord. It accepts connections from Minecraft clients and redirects them to the proper servers based on a number of different rules, so you can give your players a nice, pretty url like play.mydomain.com instead of s1.myserverhost.com:9092. At present, CraftProxy redirects Minecraft connections based on the domain you connect to, however in the future it will be possible to redirect based on other conditions, listen on different ports, and other features. So, you can have something like this:
CraftProxy can do this because of the way the Minecraft protocol is structured. The first packet sent to the server contains all the information CraftProxy needs to know: the hostname that was entered (play.mydomain.com) and the port that was entered (25565). With this information CraftProxy selects from a configured list of servers to send the connection to.
What isn't CraftProxy?
A way to play Minecraft behind a firewall. You still need access to Minecraft.net to log in to most servers.
A domain name creator. You'll need to have your own domain name to use this. (Though, you can also redirect based on IPs, too! Just change the first URL to an IP address, and people who connect to that will be sent to one server. But, this kind of defeats the purpose of CraftProxy.)
CraftProxy is not officially released yet. However, you can get an early pre-alpha here. Please be aware that this is an extremely early pre-alpha. It has not been thoroughly tested. There will be bugs. If you do come across bugs please post them here so I can fix them.
Disclaimer: This source code is quite literally the ugliest thing you'll ever read in your life. I will be cleaning this up, however for now it's the ugliest thing you'll see in your life. That link is not for the faint of heart.
Also, if I am in violation of one of the libraries' licenses, please get in touch with me and I'd be happy to help resolve the issue.
Will this new version have chunk caching again? That was one of the best features of CraftProxy in the past, and something none of the other similar mods do. I dare say I want the chunk caching back more than the server hopping