HOP is a language for programming the Web. My cursory scan indicates that the system has roughly the same architecture as OpenLaszlo for creating web apps. A domain specific language is compiled into a combination of client side DHTML code and server side business (in the broad sense) logic handlers. Scheme inside.
Looks like a neat framework, but the downer is that it can only target standards compliant browsers, a.k.a. anything besides IEs 5 and 6.