The postcrossing official forum where you can chat with other members of this project.

Postcrossing twitter for quick updates on the project.

Postcrossing Facebook group for the users of this big social network.

Don't know Kiva yet? It's a great website where little money can make a huge difference. Definitely check this one out.

Universal Postal Union (UPU) recommendations on how to properly format an address in each country

A website with translations to several languages of common sentences used when writing a postcard

The famous and only Bookcrossing Project.

Little things on big adventures.

Allows you to track your Euro bills around the world.

The Letter Writers Alliance is dedicated to preserving handwritten letters - all sorts of goodies related with that!

The postsecret project allows people to reveal their secrets using postcards.

If you are into mail art, you should check this one out.

An Aerogramme (a letter that folds up into it's own evelope) is a wonderful way to send a message by mail. Int'l Girl Aerogrammes are wonderfully designed and come in several languages.

A great community around knitting.

A wonderful site that allows anyone to bright a sick child's day.

An interesting project for all mail art artists

A travel game website dedicated to children where they can learn about other places in the world and send postcards about it.

A blog around mail art that exhibits postcards sent by snail mail to them

A tumblr blog of postcards mail with the answer to the question: "what are you doing, you know, more generally?"

A good starting point for information on stamps, postcards, mailbox and others

A good platform for collectors, and not just of postcards!