Eric Firestone has developed a new computer on an approximate 6" by 6" board. It emulates a TI-99/4A with an IDE hard drive, 1 MB AMS memory, VGA, 3 wire RS232, USB keyboard, USB mouse interfaced to the 9938, SID, 4 Myarc floppies, and supports most all of the modules out there. It's a hardware take-off of PC99. It has a cartridge slot, along with PEBox/firehose interface. A few more details are at: http://caddelectroni...duct/cadd-995c/ . It's got like 4 microprocessors on board to handle everything.
It is not cheap at $799 USD, but has quite a bit of potential. I'm getting one of the prototypes to be replaced/traded with the final version when his next run comes in. He is also developing a couple of other boards to attach to opto-isolate the board from the PEBox or cartrdge port.
Eric has also hinted it may be able to emulate more than just the TI-99/4A which also stoked some extra interest on my part. Nothing else I am aware for anything other than a TI-99/4A has been done to this point in time. I'm waiting for the next offering of Matt's sidecar TIPI to add that to the setup, then it would be internet ready!