Try the Plugable UGA-2K-A (http://www.amazon.com/Plugable-Multiple-2048x1152-1920x1200-...) to add another 24" monitor.

Or you can wait for the ViDock G4 Micro (http://www.facebook.com/VillageViDock?sk=app_202980683107053...) which allows you to use an external graphics card with 2 displays - full GPU acceleration.