There is a very useful and often used functionality in Blender: Limit selection to visible.
For all of those who suffer the pain of no short-cut for it - here is a quick tip how to make one for yourself in 2.55:
- Go to User Preferences, select the Input tab (ctrl+alt+U )
- Expand 3d View and then Mesh section, click Edit.
- Scroll down where you can find the Add button - add new section, expand it.
- Fill the relevant fields with the values presented in the attached screen
- Remember to assign the short-cut most convenient for you and save the user preferences
Happy blending!
