Thanks, Ben, for letting me know about these.
1) Here's a shortcut for opening a new tab and entering a new url in said tab. Type the url in the current tab and hit Alt-Enter. That will take your url and open it in a new tab, leaving your current tab intact.
2) Alt-D puts the focus in the address bar so you can go to a new url or what-not. Hitting F6 works sometimes for this, also, and actually toggles between the main window and the address bar. This is nice if you want the focus on the web page itself for scrolling with the arrow keys.