If you collect postcards or like to remember where you been to, than this is a great idea for you simple to do. Simply bind the postcards. its as this. 

1. get postcards (doesn't matter is they are written on or not)
2. punch holes in them (preferably using a hole puncher)
3. line them up and put them in order
4. cut up pieces of ribbon or string long enough to be threaded through and tied in a knot (doesn't matter what type or what colour)
5. thread the ribbon or string through the hole and tie a knot

Extra Tip:
If you don't like the idea of having a o postcard as the first thing you see. create a title page (the size of the postcards of course)

Have fun!!!!!!!