The Way We Was:
Broadcast Date 1-31-91
Plot : Homer asks Marge to the prom, but she goes with Artie, and ends up realising Homer is the one she should have gone with. There is a Dark Side of the Moon poster in Homer's room.
Homer Goes to College:
Broadcast date: 10-14-93
Plot: Homer has to go to college to keep his job, he joins up with some nerds and plays pranks, including stealing a pig from a nearby college. There is a Pink Floyd poster in the dean's office.
Broadcast date: 5-19-96
Plot: Homer kicks Peter Frampton's pig launcher at a rock festival, and Pink Floyd's pig is shot out. Frampton states that he got the pig at Pink Floyd's yard sale.
The Old Man and the Lisa:
Broadcast date: 4-20-87
Plot: Mr. Burns losses his fortune and has to start making money from scratch. Burns tells a recycle vendor, "Shine On You Crazy Diamond".
Homer becomes a hippie...he puts [peyote] in the juice and the entire town is wired...Ned Flanders stops his car at an intersection and the hammers from the wall march accross the street (they subsequently turn into the rolling stones lips to kiss him)
Mr Burns loses all of his fortune and rebuilds it through recyclables...he gives a can to the hippie junk dealer and mr burns says "shine on, you crazy diamond!" to which the 40 year old hippie replies: whoa, man...you're livin in the past! - Baron Nacho
When the workers of the nuclear plant are on strike (I think that's the one), Mr. Burns comes by and says "Shine on, you crazy diamond!" - Jerome
(I think the SOYCD ref has been used more than once. I've seen it but don't particularly recall it being in either of these episodes. - Bedwarmer)
In the flashback episode where we learn how Homer and Marge met, Homer has a Pink Floyd poster on his wall. Also a Led Zeppelin poster, IIRC.
In the episode where Homer attends Springfield University, the dean has a DSOTM poster in his office. - Raf
There's also the scene with the inflatable pig in Homerpalooza. Peter Frampton got it at "Pink Floyd's yard sale" or something like that.- Diane Hall