Daily Demotivators - I got a whole section devoted to those.

Informative Animals

Advice Dog

started it all, either as something to do with internet security, or a fansite forum, according to Encyclopedia Dramatica.

Check out the Advice Dog Generator.  Now you can make Advice dogs as well!

Many other animals stemmed off of advice dog's success as a meme.  Find a full list at Encyclopedia Dramatica.  But here are some of them.

Insanity Wolf

Neutral Dog

Socially Awkward Penguin

Horny Pug

Philosoraptor

Remorse Dog

Advice Bitch

Some others

Moar Pics

most of these pictures STOLEN from Encyclopedia Dramatica