A Little review of Gerben's Site!
This site by Gerben van Gelder currently under construction may be the best to date. Great maps, charts, information and explanations as it relates to each issuing identities including an ease of navigation of the site. I have contributed some information to this site. In theory this site is to be limited to issuing entities noted in the 4 largest international catalogues, Scott, Stanley Gibbons, Michel & Yvert & Tellier! This limit is a strong base but there is more and the site does explore some of them.
Rating on website 7.5. Please note that this rating is this low due to the fact it's not complete. It will very likely be the best site available when completed.