Here is a collection of projects that are really part of a bigger project, but that might be useful for your projects, e.g adding an LCD screen or using a GPIO pin.

• Two Line LCD Character Display
  
• I²C LCD Display
  
• 2.5" SPI LCD Display
  
• GPIO LED Control
  
• GPIO Inputs - Button LED Control
  
• GPIO Inputs - LED Control via a button and Interrupt
  
• gpio_control_from_command_line
  
• LED PWM Control
  
• How to use a Stepper Motor
  
• Remote Fire Camera via GPIO
  
• Using gphoto2 to Control a DSLR Camera
  
• IC2 LCD Display