The expensive and worthwhile habit of traveling has spawned other hobbies for enthusiasts, including photography, and postcard, stamp and coin collecting. Nowadays, travelers will not only hunt for beautiful landmarks and tourist spots to visit and photograph, but will also look out of the best places to get their souvenirs from ~ postcards they will be sending to their postcrossing friends, or rare local stamps they will be swapping with fellow philatelists and obscure places to buy gold coins that they are sure their numismatist friends will adore. These hobbies are loved even by non-travelers, since even without leaving your hometown you can easily look for people to swap these treasures with using the internet and other forms of media.
Ofcourse post card and stamp collection is becoming a most common hobby for almost every one nowadays. And like you said you can do it sitting in front of computer over Internet.