I have send the link because its the only design i know that allows to control something through Internet (i assume wifi too),
it uses the TCP or UDP protocol and has explanation about the protocols too, perhaps you need some other custom protocol but i can't help you on that.
The specific design uses a server on the avr and uses a computer to send or receive info or control something, i thought you wanted something like that.
I only know what i read there so i can't tell you any more than you read in the articles.
Alex