Perhaps my favorite way of collecting stamps has been to collect the letters, airmails and postcards sent to me and/or my spouse from countries around the world.  I find that the more remote or “exotic” the country of origin the greater the thrill, but sometimes the sheer esthetic appeal is all you need.  Unfortunately, the ability to practice this type of collecting has been significantly diminished in the last decade or two with the advent of electronic communication.  I was fortunate to be publishing in the scientific literature for many years before pdf’s of scientific papers were available, and the only way for someone to receive a copy of your paper was to request a reprint through the mail.  Consequently, I received, and collected, many of these postcard requests – a favorite example is shown below from the “CCCP”.  A larger collection of these can be seen on the pull down menu under Thematic Philately on this blog.