Hi
to my research, the author of MenuBackend has not been aktive since 4 months. Another problem is, that there are several menu libs out there. Several weeks ago, i collected some of them:
Library Name: LCDMenu2
Download: http://arduino.cc/forum/index.php/topic,73816.0.html
Library Name: LCDMenu
Download: http://arduino.cc/forum/index.php/topic,96104.0.html
Library Name: MenuBackend
Download: http://wiring.uniandes.edu.co/source/trunk/wiring/firmware/libraries/MenuBackend/
Library Name: LCDMenu
Download: http://www.metalgecko.com/arduino/LCDMenu.zip (does not exist any more)
Library Name: Arduino_LCD_Menu
Download: GitHub - DavidAndrews/Arduino_LCD_Menu: This library creates menu systems primarily useful for 16x2 or 16x4 LCD displays.
Library Name: MENWIZ
Download: GitHub - brunialti/MENWIZ: ARDUINO LCD menu library: short user code to manage complex menu structures
Library Name: phi_prompt
Download: Phi_prompt | LiuDr Electronic Solutions LLC Official Blog
Library Name: MenuSample
Download: Arduino WiFly Driver - Browse /MenuSample at SourceForge.net
Library Name: M2tklib
Download: Google Code Archive - Long-term storage for Google Code Project Hosting.
Not too many Arduino users add displays. And only some of them decide to use a menu lib.
Of course i would suggest to use "m2tklib" (as author of the lib 
)
"m2tklib" can call sub menues.
Oliver