The first credit cards were given out in 1950 to just 200 people. They were only accepted in 14 restaurants in New York.
Source: About.com (http://history1990s.about.com/
od/1950s/a/firstcreditcard_1.htm)
The Barclaycard Cashback currently offers 4% cashback on all spend (up to £30 per month) until 30th September 2008. In addition 0% on balance transfers for 12 months and 6 months free gadget insurance if you apply by the 5th September 2008
Min Age: 21 Years
Minimum Income: £10,000 p.a.