I wouldn’t count repurposing an (as of then) unaired pilot into flashback footage as a clip show.
THE INCREDIBLE HULK did a clip show that actually moved the plot forward: injured and stranded with a bandaged amnesiac, Jack McGee relates his perspective on the various inexplicable near-misses he’s had pursuing the closest thing to Bigfoot – and why it’s so important to him to someday break that story.
The episode ends after Banner recuperates by hulking out, and cue a minor epiphany for McGee: he now knows (a) he’s doggedly on the trail of a kind-hearted little guy who doesn’t want to hurt anyone, and (b) how the Hulk disappears after wreaking havoc: by turning back into an amiable hitchhiker with sad walking-away music.
Castle did a clip show a little while back when the network bumped up its episode order for the season. The frame story they hung the clips on – Beckett accidentally activates a bomb, and she and Castle look back on the progression of their relationship – was actually pretty decent. Sometimes it scarcely felt like a clip show.
The series finale of the X-Files was a clip show. There’s a trial where the protagonists pretty much go through the series mythology step by step, accompanied by clips. I recall being pretty unsatisfied, as it didn’t add any new information to make the whole thing less of a mess.
The Legend of Korra had a clip show in its final season. Mostly standard clip show fare, but one of the segments consisted of a character taking all the major events of the show and mashing them together to create a crowd-pleasing, mostly nonsensical story.
The Community episode is definitely my favorite take on clip shows. The clips from non-existent episodes hit the right balance between “I can sort of see how that could of been an episode” and “that’s a ridiculously stupid episode idea” and did a good job of poking fun at the show’s various conventions.
One of my favorites is from the last season of The Mary Tyler Moore Show (the episode is called “Mary’s Big Party”). A running joke throughout the entire series is that Mary, despite being perfect in almost every other way, always throws disastrous dinner parties. This time, however, is sure to be a success–Mary has a special celebrity surprise guest, Johnny Carson! Unfortunately, disaster strikes again. Johnny is running late and the power goes out.
The party guests spend their time in the dark discussing Mary’s other horrible parties. (That’s where the clips come in–any framing scenes in the apartment are completely dark.) At the very end, Johnny Carson does show–but the power is still out and you only hear his voice!
I always preferred the Kill la Kill recap episode. It’s just the right length of original and old material.