UI in Browsers - two observations

Being the user interface nut I am, every time I use an application, I mentally 'take apart' its UI to remember the stuff I like and don't like, to be able to apply that knowledge to my own applications. Object-Oriented programming (in particular with Cocoa) has made this extremely easy, as a lot of the stuff that makes a GUI great can be packed into a nice reusable class and thus only needs to be written once. Here's today's discoveries:

• Firefox has URL completion in its Preferences! E.g. when you enter the "Home Page" URL to show in newly opened windows, it will offer completion suggestions.
  
  While most browsers these days provide completion in their URL bar (some better than others, but that's a rant for another day), almost none of them provide it anywhere else where URLs are specified. It's great to see such a seemingly obvious but completely overlooked UI gem come out of the open-source world -- maybe there's hope yet...
  
  Now, wouldn't it be great if there was a URL text field to provide that behavior across all apps? I could see something with auto-completion and a little popup menu like in NSSearchFields that shows the bookmarks from the user's browser (filtered by scheme, of course), and drag and drop support so it can create URL clippings on the desktop, which is one of my most-used Mac features...
  
  Right now I don't have a web-enabled app that takes URLs, so I won't be writing it anytime soon, but if anyone else does, let me know.
   
• On the downside, there's a keyboard shortcut that's been causing people around me grief: Many browsers accept the delete (backspace) key as a shortcut to the "back" button. Now imagine my dad sitting at the computer, accidentally clicking while trying to correct what nonsense Safari's auto-completion has done again... It removes the selection from the URL field and ... huh? Where'd the page go?
  
  Not to mention that "delete" is inherently a dangerous key. Using it for such a simple shortcut as "go back" is counter-intuitive and only waters down the meaning users have attached to most keys. Reserve dangerous keys for dangerous actions, and harmless keys for harmless ones. That way, the connection between "be careful" and the delete key gets hard-wired into the user's brain, and they're encouraged to verify the cursor is where they expect it to be when they fearfully hesitate that split-second before pressing delete.
  
  Besides, in an application where you frequently enter text, what business does the app's developer have placing a shortcut on a common text-editing key that doesn't use a modifier key? I'd say go with Command-LeftArrow (Control-LeftArrow on *nix and Windows) for back, and make delete beep when pressed without a keyboard focus.