Go to DeviantART or Interfacelift or similar site and find disk icons with labels (like Pry Hardware by Jonas Rask), then use CandyBar or a similar application to change the disk icons. Then the loaded media can be identified by the label on the icon.

OS X has already the proper icons for each kind of optical disk, they are stored in IOCDStorageFamily.kext, IODVDStorageFamily.kext, IOBDStorageFamily.kext (for CD, DVD and BlueRay disks, respectively) located in /System/Library/Extensions. Finder use them when you mount the disk and they are more legible than the Pry Hardware one (Pry icons have really tiny labels on the disk icons).

But this does not solve the problem, as those icons are used only if you mount the disk in Finder. If you choose to ignore the blank disk (say you want to use Toast or Burn or anything you like), you need something else like the two CLI commands above (drutil or system_profiler).