Having just recently transitioned to Visual Studio 2010 (finally) at my day job, I found myself in a bit of a predicament.
Previously we'd been using VS2005, for which there was a little extension called MetalScroll (based on another named RockScroll); this extension changed the scrollbar into an actual thumbnail of the code in the editor. For very large and complex files, this makes navigation considerably easier and quicker because you can learn the code's physical layout and identify important locations in the code by sight.
Unfortunately, as of VS2010 all extensions have to use WPF; MetalScroll was a Win32 extension and the author had no interest in rewriting it for the new version.
There are some other scrollbar replacements available for VS2010 (AllMargins by David Pugh, and the modified version of it which is included in Microsoft's Productivity Power Tools for VS2010).
These have some nice new features, like showing a code preview tip window when you hover your cursor over the scrollbar, but none of them quite stack up to MetalScroll as far as navigation goes. AllMargins's included StructureMargin extension just shows an abstracted representation of code blocks and regions, while PPT's "full map" mode only renders every Nth line in large files, so the scrollbar image is not at all representative of the actual code layout.
Fortunately, while the source is not available for the improved version of StructureMargin that is included in PPT, the original one from AllMargins is. So this weekend, I decided to try my hand at tearing it down and rebuilding it into something approximating MetalScroll as closely as possible. Here's the result:
I call it MetalMargin (very creative eh?). It retains some of the features from AllMargins that I liked (the code preview on mouseover), while removing and rewriting the abstract structure view into a direct physical preview, which uses your own VS color settings to draw the thumbnail.
It's available here if you're interested in giving it a try. I haven't tested it anywhere other than my home machine yet, so if you have a "clean" VS2010 environment which has not had 2005/2008 installed also, you may be missing some dependencies. YMMV 