I learned about ajax this week in class. I knew about it in the past but I haven't had much experience implementing it. Seems like a really good way to send and receive data quickly.
The basics of AJAX is that you create a function that will serve json whenever it is called. This function is tied into a URL that can be called with optional parameters. Then you can have another program, be it a web client or desktop software send a request to this URL. The program then receives back json formatted information it can use.
I will be using AJAX to implement my final project for class. I'll be able to run the python pyBotWar program on a server with a modified AJAX function that sends out the state of the game. The client can then ping this function periodically to get information about robot position, angle, health, etc. and draw the state.