Well, I'd say something along the lines of C++, but you might want some sort of socket library to make the network programming a bit easier. This one seems to be fairly popular: http://www.alhem.net/Sockets/
And of course you're going to need to write a decent parser... you might even want to download a premade one to save yourself the trouble of coding one.
Rather than trying to reinvent, take a look at the source code of Mozilla Firefox browser and build your own one from that point. This way you can actually implement some of the custom features you so much wanted with the plus being you don't have to code the same thing.