Sturgeon's Law: Ninety percent of everything is crud.
And thus most April Fool's Day jokes are crud.
The best I've seen this year is either the Astronomy Picture of the Day image of
water on Mars or
howardtayler's "moving" (or is it
moving?) of
Schlock Mercenary off of Keenspot.
The best I can recall from the past is the Great Comics Switch a few years ago - it didn't mess things up much if at all and didn't slap the comic reader in the face with idiocy. The next year, however, a truly idiotic stunt was done. Some comics were flipped left-for-right, making them readable only with difficulty.
A faire related website a few years set up the front page as if it had been change to a county or state fair site, which made it useless for the actual purpose for a day or so. This has been an on-going thing. A couple years back the guy who runs the site put the domain on ebay as the joke - except someone made a sizable bid and bought it - even with handing it right back, ebay wanted the seller's fee. The lesson was not completely learned. Now he just messes up the web-board of the site. This year it posts in StUpid lOSer mIXeD uP CaSe. Blargh.
Slashdot is getting filled with useless fake stories again this year. Had the folks running slashdot really been thinking they'd have simply re-posted one of the real stories over and over all day - poking a bit of fun at both themselves and those who shout "DUPE!"
Back when the magazine Popular Electronics still existed and used that name, they'd have *a* column and maybe *one* story that was an April Fool's Day special. That wasn't too bad. But they hurt themselves once when it seemed every story in the April issue was a joke. There was no April issue, really. It was replaced with this fake. They got complaints - and deserved them.
I suppose I'll now be accused of not having a sense of humor. An accusation which is itself humorous. It's simply that I prefer things claimed humorous to actually be funny. Most April Fool's Day jokes are not.