While it may be possible to add a string of javascript to the end of the URL in order to fill out the forms, I don't suggest it. It is quite dangerous. Someone can easily find your password by looking at the URL, or even tracking your history. Say you're using free wifi at some random coffee shop, say someone is watching the packet flow and there is your password! Exposed to everyone. A safer idea would probably be to have your browser either remember your password or simply add a cookie by clicking the "keep me signed in" check box.