I am lookong for some broker that allows ETF trading, and have trader with API for java.
I found http://www.deltastock.com/ , but it seems they do not have java API. They have something like API for VBA and C#, but I cannot see the way how use their API in java. Their API has something to do with ActiveX - http://www.deltastock.com/english/platforms/forex-api.asp
This post would be a good starting point. If you are interested in ETFs IB would be the best. They are generic broker where you can also trade ETFs.