Lest you think that Missle Mail was just a crazy idea from the 1950s, think again:

Technologists like Robert Zubrin, of Mars Society fame, think that rocket mail, or at least ultra-elite business package delivery, may become commercially viable with the development of fully reusable launch systems, particularly single-stage to orbit vehicles. Such systems would allow package delivery anywhere in the world in 30–45 minutes. This idea has been forwarded by Zubrin and was the original business plan behind Pioneer Rocketplane (now Rocketplane Limited, Inc.), which he co-founded. Zubrin has since left the company, which is now focused on pursuing a somewhat more conventional space tourism strategy. The potential of package delivery with reusable launch vehicles is discussed in Zubrin’s book Entering Space.