Zooropa is great.
Numb is a good song, I'm just not sure it's a good U2 song. I liked most of Achtung Baby though.

The Orb jumped the shark with Pomme Fritz -- their remix work is still brilliant but there hasn't IMO been a good Orb studio album since UFOrb.

The Stone Roses jumped the shark with Second Coming -- although maybe this too escapes under the "anything would be a letdown after The Stone Roses" clause.

The Happy Mondays, Yes Please (not so much jumping the shark as snorting it).

The Pet Shop Boys, Release.

Peter