Now, "CouchSurfing" is a registered trademark and a commercial company, I wouldn't call it a concept. To call it a concept is can in my opinion be compared with calling Twinings a category of drinks, or using the word "Ob" on the tampon concept.

The idea of home hospitality is age-old, I think Cervas was the first, though they have grown fairly obsolete after the age of Internet.

I've been hosting since 1998 (first through my own web page, later the Hitch Hikers Home Base, then Hospitality Club, now through the BeWelcome website), but have never been member of CouchSurfing ... just because ... I didn't like the name :p