While looking on adafruit website and searching for a small display which might work with
HDMI, I found the following OLED Display - link.
It's a monochrome display with
128x64 pixels. And the best thing about it is that if offers an
I2C interface and is cheap. You won't find many display screens featuring an
I2C interface, mainly because the interface is lacking in bandwidth.
Another solution I have found is this 5 Inch HDMI Screen. And it's still from Adafruit.
The best thing about this one is that you can connect it to the
Raspberry Pi through the
HDMI connector. It's that simple! No wires at all.
The good thing about this one is that it offers the full blown experience of the
OS - you can actually program on it and that to me is really cool.
The bad thing is that it's more expensive and for your project this might not be needed.
All after all, it depends on what you're trying to achieve.
If you just want to experiment with displaying
circles, then this little display is for you.
If you need to have access to your Raspberry and don't use a laptop for remote controlling it, then the
5 Inch display is for you.
Let me know if there's anything else you want to know.