Spidey Super Stories, on PBS
Marvel Database; Wikipedia; YouTube

This was a recurring sketch on The Electric Company, and pretty much the only recurring segment I really remember from watching the show when I was a little kid. I've always remembered the theme song, or at least half of it; Wikipedia has four verses, but I only remembered the first two. (But watching a couple of videos on YouTube, there only were two verses, so maybe the other two were in episodes I never saw.) And I remember Spider-Man not speaking, but his words appearing above his head in speech balloons, like in the comics. (Although all the other characters can be heard.) And I remember a "hiccup" sound whenever one of Spidey's speech balloons appeared (though watching a couple of videos on YouTube, I find that various other sound effects were also used). I don't really remember much in the way of actual stories, though I'm sure they were all fairly silly. Anyway, one of these days I should try to watch more episodes on YouTube.

Note: this is one of few "shows within a show" that I felt deserved to be included in my microseries section. Others can be seen under Sesame Street.