I'm currently thinking of the interface of my project. On my DEV board, I just use LCD 2*20 (4bit), and buttons. Ideally, I'd like to have an I2C LCD (4*20, or 2*20) and buttons, also on I2C interface (5 mini). I found the spyglass from procyonenginnering (I love AVRLib), but it looks to be unavailable now. the price look very interesting, but I have no answers from them.
I used to work/develop with crystalfont / matrixorbital LCD+Keypads (serial/USB), but their I2C products are quite expensive.
I'm also looking at GLCD+touch panel, but this is an other story....
So if you have any links to interesting LCD+keypads using I2C, I'd be very happy !