I just want to mention the names of the top two iRiff creators other than ICWXP that I have been enjoying the hell out of lately:
1. Just Andrew. He seems now to be completely inactive, having mentioned at one point on a page here that he had a new baby in the family - which will do that sort of thing. Those iRiffs he's done, particularly War of the Robots and Warning From Space, were great. I bought his entire catalogue...primarily because Andrew carries things off on his own pretty well. This is not easy in iRiffs, as a rule, for me to enjoy.
2. Atomic Treatment. This is sometimes just Bryan Sample, sometimes him being joined by Mr. B Natural. I like the duo pieces better, particularly Sons of Hercules Vs. The Mole Men, but Sample can do a one-man job, too...although not with Andrew's attitude and humor. I like the way the later pieces are interspersed with "commercial breaks" showing ancient TV ads, also riffed. AT does appear to still be active, which is nice.