I would like to introduce new category of collecting stamps. In czech it's called "známkové zem#283;" and I would translate it like stamp's countries or maybe easily - geographilately.
I'm not sure if the translation is correct, but maybe you know the catalog Philatelist atlas by Mucha and Hlinka, which was translated into different languages.
So what is it all about? The main purpose is to have at least one stamp from each country, that has issued any stamps. It doesn't seem to be so hard, but there is more than 1500 countries (punctually 1539).
Let's make an example. If there is someone, who collects Canada, then they will agree with me, that there are many issues - Nova Scotia, New Brunswick, Prince Edward Island, British Columbia (and Vancouver), Vancouver, Newfoundland, Canada (British colony - till 1867) and Canada (dominion - since 1867 until today). So it means, that one current country means 8 "stamp countries".
This is more interesting in Africa, because there are many occupations and occupations of occupations :) and issues from tribes in South Africa such as Witu, Venda, Transvaal, Cape of Good Hope and many others.
For me this is the best "topical" of collecting stamps, because it combines all others. There are the oldest stamps together with the new ones, animals, ships, etc. with "heads" (bust - I have no idea what word do you use for this). It combines geography, history, current world and stamps.
And if you want, you can add some local issues from WW2 or from Columbia and Brazil and Russia and form other countries. It's just on you. There are no strict rules (maybe except the list of basic countries). All other informations you can find on the website geophila.com or maybe on
http://www.postoveznamky.sk/znamkove_zeme.php .
I hope that you understood me, 'cause I'm not the native speaker. I hope that this article was at least quite interesting for you. I'm gonna scan one continent for you, so you can see, how it looks like when it's mostly complete. I hope that I can manage to do it in week. Looking forward to having an active discussion.