I just went on a binge this evening, if you guys are at all interested in this beautiful art style...check these guys and references out!
http://colormemucha.tumblr.com/archive <--- a /pretty/ good blog, doesn't always have good photos but had enough for me to bookmark them
http://www.mcbridegallery.com/nizovtsev.html <--- awesome painter.
http://www.amysol.com/sectionsHTML/gallery/index.html <-- not exactly art nouveau but she's pretty close. You could also check out http://www.audrey-kawasaki.com/ who is kind of in the same flowy/asian style
http://www.identifont.com/show?PLE Very simple reference I like to use.
Here also http://www.flickr.com/groups/artnouveau/pool/with/198008690/
http://preview.tinyurl.com/7yqdtx6 <-- My favorite Art Nouveau artist!!
http://preview.tinyurl.com/6s2cgrn <-- My second favorite Gustav Klimt
http://preview.tinyurl.com/6wv2l7f <--- My third favorite Felix Mas
http://preview.tinyurl.com/7s5xk6g <--- My fourth Aubrey Beardsley