I don't remember if I had posted this site before or not? Perhaps I did on another link? It is a site that isn't currently active, but it does have a lot of odd stamps that have been identified and is good for researching stamps that are stumpers. http://www.raster.it/stefano/a/
Another interesting links. http://www.nfldstamps.com/ http://www.briefmarken-kiloware.eu/ (per kilo stamps)
Here's a great source for stamp terms and their definitions. http://arago.si.edu/index.asp?con=3&letter=p
I know differentiating some of the Washington Franklin issues of the United States can be difficult so I have linked a nice site with some good information. http://www.jamesdire.net/W-F.html This is actually a link from the first website, but it is a great site for distinguishing the different "types" http://www.1847usa.com/
Learn more about Chinese stamps on this link, need Google translate on this. http://max.demichel.free.fr/Legranddragon.htm
Nice stamps featuring dinosaurs on this link. http://www.search4dinosaurs.com/postage_stamps/CentralAfricanRepublic_Dinosaurs_Prehistoric_Animals_Postage_Stamps.html
