Now there are simple led screens out there right now which work on serial communication and only display text. That might be good enough for you, but I like flexibility. With a GLCD, I can use different fonts, show pictures, and even animations!
What's also really nice is that the GLCD I'm using is only $20. Granted, this is a little bit more involved to program and to get to work above the super easy Serial.print("Hello World") commands.
As always, I made it at TechShop.
Step 1: Materials
1. Arduino Uno $40
This CAN work, but it takes up just about all of the pins. If you want to do anything else, I recommend a Mega $60
2. GLCD $20
based on a KS108B lcd
4. Header pins (row of 20)
5. Jumper wires
6. 10k ohm potentiometer (for contrast control)
7. 1k ohm resistor
8. soldering equiptment