"Creeper" nav bars (an appropriate term, I think) are partly a consequence of mobile devices not letting you instantly jump to the top of a page. Mobile devices should offer a snappy, intuitive way to jump to the top or bottom of a page.
Opera on mobile had an awesome implementation of "jump to top": You scroll upwards twice or just quickly enough, and if you still have a long way to go, a button pops up for scrolling automatically to the top. I wish this was implemented universally in Android. http://lifehacker.com/5784500/opera-mobile-11-is-a-zippy-bro...
You can jump to the top of most native iOS scrollable content, including web content in Mobile Safari, by tapping the system bar at the top of the screen