The KTM-S1201 serial LCD module
This is a very cheap surplus serial module that is easy to interface to. It is a 12 digit seven segment module. It can't do letters all that well since it is a seven segment display, but you can do most of the letters after a fasion. And for the price, it is hard to ignore. These are currently selling on Ebay and around the web for $2 or so. Compare that to the $20-40 you would pay for other serial LCD modules. Sure you could get a parallel module for a similar price but do you really want to mess with all those pins?
Here are some links and example code to get you up and running with this great little display.