SAJAX
SAJAX routes calls directly from Javascript into your server-side language and back out again. So, for example, calling a javascript method "x_calculateBudget()" will go the server and call an ASP(temporarily removed due to bugs)/ColdFusion/Io/Lua/Perl/PHP/Python/Ruby calculateBudget() method, then return the value in javascript to x_calculateBudget_cb().