The Pigpen/Frankie Teardrop mash-up was definitely inspired. Weirdly enough, sometimes the Frankie Teardrop lyrics and the "four day creep" riff actually complimented each other. I don't know if Tom knew about it ahead of time, but it made it even funnier.
Darren's call was fun as well. I'm sure part of it was an excuse for Tom to let off steam, and it was a dead on critique of the current state of the comedy business. There's definitely a formula entertainment executives are using to put together most "comedy" shows. It's either "comedian makes fun of videos on You Tube" or "comedian talks about issues of the day with other comedians (which are essentially televised podcasts)". It makes shows like "Nathan for You" all the more special because they are trying to do something different.
Honestly, I boggles my mind why Tom has struggled so much to get his own (for profit) stuff going. Honestly, I think does boil down to the art vs commerce thing. What Tom is doing I think perplexes executives because it takes time to really digest and understand the show. Almost every podcast is doing the same thing (comedians interviewing comedians or people riffing on pop-culture) so it's easier to translate into a show or make it fit a cheap formula. Tom (and Jon) are world building with dozens of characters, telling personal stories, breaking formulas (puppets on the radio!), it's just over the heads of too many people. It's the "Big Bang Theory" vs "Parks and Recreation" argument. One is creatively superior, but for some reason the it doesn't get the ratings the dumber show gets.
I think the Best Show DVD is an example of what Tom could do with his own show and it would be amazing.