If you just want to play around, take a look at www.fin24.com
Slow as hell but you can get a feeling for trading stocks.
Can't remember by how much their data is behind, a lot of stock data is available, they do include a admin fee on each transaction (0.3%), but they do not look at volumes. (in a real system you can only sell/buy if their is enough stock volumes available)
Also take a look at the bloomberg app on blackberry. List all info on JSE stocks.
The problem with share trading is that it's quite a gamble. And to really make a good deal of money you've gotta put in quite a bit.