I have tried out Bitcoinica, and although it is complicated i like it a lot!
What confused me is the "Maintenance" amount shown in the Account overview. It looks like it is not explained on the website.
If it is the fee, it is quite steep, i must say..
http://en.wikipedia.org/wiki/Margin_%28finance%29#Initial_and_maintenance_margin_requirements
– lemonginger Sep 09 '11 at 21:36