Newhaven Display (newhavendisplay.com) offers a collection of 10 different character LCDs in 2x16, 2x20 and 4x20 formats that are exclusively serial inputs -- I2C, SPI and Async TTL -- and reasonably priced at $15 to $20 U.S. I have a couple of the 2x20's, and they work nicely in all 3 interface modes. Nevertheless, this is a very interesting project as I (like everyone else) have a drawer full of parallel interface HD44780 type LCDs that will be put to better use with this serial interface. Many thanks, and I'll provide you feedback if I have anything useful to contribute.