U.S Share Dealing for UK Citizen

Can anyone recommend a U.S based institution that allows a UK citizen to sign up and speculate in the stock market? It needs to be okay for a UK citizen to sign up and would not need a U.S social security number.

More detail in your questions might yield better answers!

What is it exactly you want to do?
Where do you live?
Why does the institution have to be US based and not UK based but allow US stocks to be traded.

Try interactive brokers for day trading. They have a UK office.

Pretty much any UK broker will let you trade US stocks. You can even do it through an ISA i think.