If you are looking for a new online broker, there is a great summary chart here:
The chart covers equities, options, futures and forex. It would be even better if they would add columns or another chart for mutual funds and bonds.
One thing that stands out for most of the firms is the huge spread in the interest column between what you earn on credit balances and what you pay for margin. The only firms that offer somewhat reasonable margin interest rates are Interactive Brokers and Just2Trade.