The Bibliothèque Nationale de France (BNF) has a very cool online exposition on Daumier, it’s MASSIVELY illustrated and went online smtg like 2 months ago, so it’s new and classy and all :
http://expositions.bnf.fr/daumier/index.htm

For the moment it’s just in french, which is a shame ’cause explanations are really cool and exhaustive, but you can still look at the great pictures !

And at least you don’t have to register to access the database !