I use Standard Bank Online Share Trading. It's a bit expensive but the resources and graphing software is second to none. I'm very happy with it.
Some features of the R160 per month Viewpoint package:
Live prices (no delay) always.
Specialist graphing software with all the indicators built in (see an example screen capture below)
Instant one-click buy and sell.
Research, fundamental analysis and professional opinions.
Live SENS news feed.
And that's just the beginning!