The following are a websites which I find particularly useful or interesting.

Buying?

If my website encourages you to collect postal history material I can do no better than refer you to  David Shaw's Postal History  website where you will find quality postal history items for sale.  I have bought from David for a number of years now and can recommend both his material and his excellent service levels.

Simply Browsing?

Some years ago I stumbled upon the website of Ron and Eunice Shanahan and found the content fascinating.  I make frequent visits to this site - particularly the Letters from the Past  Section.  This website was a significant influence in my decision to kick off my own website.