Do any of these have a Javascript interpreter?

No. They're all vanilla WebKit with different chrome.

None of them even screw with the rendering engine, much less have their own.

Could I make one that remembers passwords. I hate having to retype them in all the time! Oh and also I want to replace it's braindead caching scheme. If I switch to a different window, and switch back, why on earth would it think to reload the page??