I tried out the site you mentioned and if the server wasn't outright lying to me this is what I got via Fiddler2:
Server: Apache/2.2.16 (Unix)
From this I could assume that the website is run via perl CGI scripts running on an Apache webserver under Unix, but then again why should I trust what some webserver tells me. :-D
As has been said before me, it is impossible to say even when file extensions .aspx .ashx .pl and .php or whatever are present it doesn't mean a thing.