Code minimap as your Qt Creator scroll bar. A tweaked version based on the pretty snappy CoolScroll by Egor Zhuk. The outlook has been modified to resemble the Productivity Power Tools minimap of Visual Studio 2010.
Just generate build directory and relevant makefiles with QMake. Customize input variables QTC_SOURCE and LIBSROOT for your particular setup.
cd <path-to-coolscroll-sources>
mkdir build
cd build
qmake -makefile QTC_SOURCE=<path-to-qt-creator-src> LIBSROOT=<path-to-qt-creator-libs-dir> ../
make
The default project settings will generate the plugin under Qt Creator's user profile plugin directory.