Hitchhiker's Guide similarities
I thought the whole "emasculated badass trying to get his mojo back" plot was very similar to the Thor subplot from And Another Thing. Interesting now that I thought that book read more like a Futurama episode than a classic Guide novel.

Gimme another space beer, Gleep-Glop.
Back when the show originally aired, they would post the episode title on mrshow.com the day before the episode aired. I remember reading "Life is Precious and God and the Bible" and just imagined some dumb hick in the audience of a daytime talk show.

I could've sworn…
…that it was called "Harry Chang's 'From Outer Space'."

What was the meaning of life anyway?
The whole eternal reccurance thing was interesting, but some physicists speculate that once the universe expands to a point, it will contract and time will start moving backwards. That would've been an interesting way to solve the "different universe that's exactly the same"…

an impromptu concert by Boz Scaggs
Quotability was always the show's biggest strength:

might be slightly off-topic, but
It recently occured to be that Lisa's Wedding takes place in the year 2010, and the only thing they got right about the future was that Heather Locklear is now a dangerous criminal.