*BA do an Amex that can get you into one world.
*bmi can do one that can get you into the Star Alliance.
*The star alliance is currently the biggest alliance in the world with 16 members and USAirways joining later in the year.
*There is a special offer with bmi at the minute where you receive a free flight for getting bmi Mastercard.
*bmi "Diamond Club" earns you miles quicker than BA
*bmi miles can be earned on Star Alliance airlines, Virgin Atlantic and South African Airways and spent on those mentioned and also bmibaby.
You can apply for bmi Mastercard at www.flybmi.com
Hope that was useful.
(P.S. It wasn't intended to make that sound like an advert!!!)