I use Swiss Post Box, run by the Swiss postal service, and am very happy with them:

http://www.swisspostbox.com/

They have various receiving addresses in Switzerland, France, Germany, Italy, and Austria, and notify you by email when you have a letter. You can then choose to have your letter scanned (and readable on their website), forwarded worldwide (you pay for the onward postage), archived (you pay for storage), or shredded.