I have seen the new CQAR from BAE Systems UK. It takes the ARINC 573 from the FDR feed (or RS232) and sticks it onto a PCMCIA 20Mb card. You get 20+ hours of flight data.
Perhaps not what you are looking for as they are £5000 each and you need their IHUM system running as well (which costs a bit).
What about using a notepad and pen?
------------------
400 Hertz but DC is easy