There is an application called iAnki for the iPhone which lets you navigate to a website on your iPhone, and then use that website offline. How does this work???
I must figure out how to do this. The possibilities are so tantalizing!
Update Mystery solved. I remain very impressed. It turns out that Webkit has implemented the HTML 5 standard for SQL data storage. Since Safari is based on Webkit and the iPhone uses Safari, the iPhone has HTML 5 data storage too.