Yes, banking is pretty profitable, but you have to have well over a million dollars to start a bank. Because you really make money from loans, most banks lose money on accounts that are above a certain number.
Oil is by far the most profitable industry as Exxon Mobil recently reported the highest quarterly profit ever in the history of the world by a company at around $10 billion USD.
profitable industrys would be import / export trade - this would include raw matterials including metals and fabrics, oil etc...
If you are looking for profitable individual products then i would say high value home appliances eg, showers, baths, kitchens, taps etc.... which can be brought quite cheaply from abroard and sold for much more in UK and other countrys.