I coded a Mancala game in Java for a college class this past spring, and I used the Eclipse IDE to write it. One of the great (and fairly simple) visual aids in Eclipse is
In a different question on SO (link), someone mentioned the VS 2005 / VS 2008 add-in "RockScroll". It seems to provide the "error bar" feature I was inquiring about in my question above.
RockScroll
EDIT: RockScroll also does the identical token highlighting that I was looking for! Great!
DevExpress CodeRush does this when you press TAB when the cursor is in an identifier, you can then tab through all the highlighted instances. There's also a DXCore plugin (the foundation upon which CodeRush/Refactor Pro are built) that does current-line highlighting.
Old question but... Visual Studio 2010 has this feature built-in, at last.
About RockScroll: It doesn't highlight the identifiers. It only highlights the same string in the source code! If there are similar identifier declared : ex. _test and test, and test is highlighted it will highlight the string "test" in variable _test too! And it will also highlight the same string in a method called "sometesting()". So it isn't exactly like eclipse and doesn't work for me.
There is a RockScroll alternative called MetalScroll which is essentially the same thing with a few tweaks and improvements.
Also there is a small and simple WordLight plug-in that only highlights the identical tokens.
Both are open source and support code folding which is nice.
Imho, the bar next to the scroll bar in Eclipse is a lot more elegant solution than the scroll bar replacement of RockScroll/MetalScroll. Unfortunately I couldn't find any VS plug-ins that do it the Eclipse way, so I just stick with WordLight.