I saw that Cracked has a new article up entitled “15 Retarded Dungeons & Dragons Monsters“. It’s OK, but really a lot of these monsters are just kinda stupid, not really humor-article-worthy stupid. (Insert 4e rust monster joke here.)
For those left wanting more (or better), there are some older articles along the same lines.
Head Injury Theater’s “Dungeons & Dragons: Celebrating 30 Years Of Very Stupid Monsters” and “Dungeons & Dragons: Celebrating 30 Years Of Very Stupid Monsters – Part 2” are the best IMO.
Then, Something Awful has “WTF, D&D: 1st Edition Monster Manual, Part 1“and subsequent mockings…
Enjoy!
Geek Related 
What, no love for Lore Sjoberg’s Book of Ratings entries ? (Originally from Brunching Shuttlecocks).
http://www.bookofratings.com/dndmonsters.html
http://www.bookofratings.com/dndmonsters2.html
http://www.bookofratings.com/dndmonsters3.html
And as a bonus:
http://www.bookofratings.com/artifacts.html
Great addition, thanks!
Something Awful has added more –
Fiend Folio, Part I
Fiend Folio, Part II