When I reactivated my trading account at TDAmeritrade, I found that they had bought ThinkOrSwim, which becomes their high-end trading platform. They don't mention this, but if you click to download it and you are on a Unix-ish OS, the download you receive is a shell script which checks for a JVM and installs the code. The shell script which launches the program is quite robust-looking. Unlike most heavily-multithreaded Java programs I've used, it doesn't feel sluggish. I'm impressed.
This is extremely nice and it will probably woo me away from QuoteTracker, which is a Windows-native application. QuoteTracker is a good tool, and is great for learning. It has an ad-supported Free-as-in-beer mode. TDAmeritrade had some agreement with them, and QuoteTracker is still (I tested it) ad-free if you are connected to TDAmeritrade, but the download link is broken and they seem to have stopped supporting it.
I don't have to boot Windows, even in a VM, just to have decent trading tools. This is really outstanding.
The one issue I am finding with ThinkOrSwim is a lack of good documentation. I've only found a poorly-written and unillustrated manual so far. It's completely clear that it does everything QuoteTracker does and much more. No wonder TDAmeritrade wants to get you started with it via a hand-holding phone call. I haven't received my call yet.