You can even sign up for a free email account with 6 mb of storage space. Send your cards from this site and they will make a donation to wildlife. Check out what they give you if you sign up for their services. I found 1,690 photos of Niagara Falls and 710 photos of frogs. The person receiving the postcard must have internet access.
Most cards look like they have been drawn by children.
Disney Cards -You must register with the Disney site, but they have some cute cards you can send out, for any occasion. There are some really neat Java Lake effects, where the water really looks like it's moving. You can also add music files to your cards, just pick your favorite tune. Then just send it off. Many occasions including African art, children, nature, pets, classics and more.