The E*TRADE PHP SDK is available to download from the developer platform site. Beginners and advanced developers could build their own trading application to analyze market data in real time. Resources include documentation, code examples, and developer support.
Once you get beyond the most basic map mashups, you'll run into a problem with data storage and access, because you can't hard-code hundreds of markers. It's a problem that SimpleGeo wants to fix. And from the looks of their new platform, they've gone beyond expectations.