One thing that is well done (IMHO) in Disneyland park is just that! The entertainment while you're in line!
Indiana Jones has "booby traps" you can set off (push the pole in the spike room for a big surprise!). Also, all the carvings on the walls in the Indian Jones ride are ACTUAL phrases in a rune language developed by Disney for the ride. When the ride first opened, they handed out cards to decipher it while in line (which was good, becuase the line was usually about 3 hours long).
Snow White's Scary Adventure has a little area where you can see part of the Evil Queen's dungeon workshop/"brewery" (where she makes her potions).
Roger Rabbit's Cartoon Spin also has a very interactive que!
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Knock on doors and look around! That, to me, is one of the most entertaining lines.
Splash Mountain's line has some peices of story posted along the way. The closer you get to the ride, the more little glimpses of it you can get, so it can be pretty entertaining (but is still pretty long, so bring some good conversation... or a good book).
One of the most entertaining lines to be in, is Mickey's and Minnie's house to meet the characters. There are some great photo ops (though Minnie isn't at home very often, or it's just my luck that I keep missing her).
Pirate's is an okay wait. It ranks up there with the Haunted Mansion in my book. Once you get inside the building, things are a little more interesting. In the DL version of Pirates, you can see the end of the ride from the line (don't worry though - it doesn't spoil anything). And in the Haunted Mansion, you can see the graveyard, which has some entertaining tombstones.
Now - DCA is lacking a little in that area, but still has some entertaining waits. One of them is in the Magic of Animation. Just walk into the main lobby area... it's a great place to sit and rest and enjoy the best of Disney animated movies.
Another entertaining que is for Muppet Vision 3-D. There's a lot to look at and once you get inside and the movie while you wait is fun (if you're a muppets fan).