focalist:
A simple board for use with typical LCD displays (like the 1602 standard, etc) that convert them to either SPI or UART
There was also an I2C+serial one done a couple of years back. I helped develop the Arduino library for it. Not sure whether it's still available, and I don't have the URL bookmarked on my work PC. He also sold an I2C multi-channel servo controller, which might help narrow a google search. However, I don't recommend it for use with I2C: he had problems with buffer overruns tryng to keep up with I2C (seemed to work okay at 9600 baud serial) that caused dropped characters and garbled command strings.
There's someone offering an I2C LCD controller in bare DIP form on ebay. In the UK, as I recall. Costs about US$4, plus a little less than that for shipping to the US.
One project I've had on the "someday" list for a while is to take a minimal Arduino like the RBBB, and make it into an SPI or I2C slave that would run a graphic LCD (which really suck up the I/O pins. And memory). The essence of the idea is to put all the resource-intensive parts of the interface on the slave. Then have a "stubbed" version of the GLCD library on the master that would just send commands and parameters to the slave when you do a GLCD call. It would be slower than having the GLCD connected directly, and might have to sacrifice a few library functions if they poke too deeply into the guts of the LCD or driver internals. But it would have the advantage of being otherwise completely compatible with a direct connection, and would make a lot of projects that need more I/O pins easier. Or even move them into the "do-able" category.
Ran