The idea is really nice. As I understand, it's just for companies.
I don't know about the possibilities but here are some suggestions:
You could post a number of successful trades. If it is still low, then you may think about it, but people always get inspired as they see that something actually works.
You could make videos about successful trades. Video shouldn't take the main place, but the visitor may see those videos and in addition you can post them on YouTube.
I think you could add some quotes at the bottom right of the banner (that colorful picture of hand). There should be many of them and show any random quote. It shouldn't be very eye attracting, probably something like the text at the top (
verb. exchange (goods or...). Some suggestions for quotes:
You can have everything in life you want, if you will just help other people get what they want.
Zig Ziglar
We can't help everyone, but everyone can help someone.
Ronald Reagan
BTW, here is a quote I've found while looking for the quotes above (it's probably more like a joke, I guess):
The most terrifying words in the English language are: I'm from the government and I'm here to help.
Ronald Reagan
P.S. Probably those quotes aren't the best possible, but I didn't put a lot of effort to find them, if you're going to add such thing to the website, you would probably search for more and better quotes. Here is the source I took those from:
Click Me
P.P.S. Design is pretty good, I think, I have nothing to suggest about it.