It's very need for me too.
An example:
I can block domain "google.com" for users.
But I need blocking only images from this domain.
In others proxy software it can be working, if I insert this "wildcard"
http://google.com/*.jpg
http://google.com/*.jpeg
http://google.com/*.gif
http://google.com/*.bmp
etc
How I can use that wildcard in Ebox?