I hear this question a lot:
What is the best brokerage?
Here's a short selection:
1) Interactive brokers
www.interactivebrokers.com
Commission to buy 100 shares of a U.S. stock: $1
2) Fidelity
www.fidelity.com
Commission to buy 100 shares of a U.S. stock: $7.95
3)Charles Schwab
www.schwab.com
Commission to buy 100 shares of a U.S. stock: $8.95
4) TD Ameritrade
www.tdameritrade.com
Commission to buy 100 shares of a U.S. stock: $9.99
5)Etrade
www.etrade.com
Commission to buy 100 shares of a U.S. stock: $9.99
PS: Not all brokers are available to European citizens.