There is a free bonus tool from Autodesk that provides drawing tabs. It is still available for download and even though the latest version if for 2010, it works in AutoCAD 2012 (tested with the 64-bit version).
The link above provides a single download that contains the necessary ARX files for 32-bit and 64-bit versions of AutoCAD 2007, 2008, 2009, 2010, 2011, and 2012. Read more about Drawing Tabs for 2012
Earlier today I updated a 3 year old post on Drawing Tab add-on applications for AutoCAD. I still see a lot of people not happy with TASKBAR=1, or the "Quick View Drawings" feature and fortunately there are still vendors updating these "Drawing Tabs" apps. One of the apps is no longer available, and a few have been updated over the years to work with newer versions of AutoCAD.
Topic updated 2014-07-02 AutoCAD 2014 and later contain built in Drawing Tabs, but with a limited feature set. Unfortunately, only one 3rd party offers Drawing Tabs for 2014 and none of them do for 2015.
Since AutoCAD moved to the MDI world back in 1999, users have wanted a fast way to switch drawings. Some of these include...
Set the system variable TASKBAR to 1 and you get a button for each open drawing on the Windows taskbar. This is how R14 would have appeared when you had multiple "sessions" open.
The Windows pull-down menu allows you to select an open drawing.
Ctrl+Tab cycles through drawings pretty quickly if you are a keyboard junkie.
AutoCAD 2009 added "Quick View Drawings" (Command ._QVDRAWING), but this tool can seem a bit sluggish, especially on a slower machine with many drawings open.
Many people prefer tabs, similar to those in Microsoft Excel. If none of the above solutions work for you, there are several vendors out there with add-on's that provide this "tab" functionality. I have tested some, but NOT all of these. This is not meant to be a rating grid, only a summary so that if you are looking for this type of tool, all the links are here.