mtd: looking for serial flash storage

[Brendan J Simon]

I'm looking for flash storage to put Linux and a root filesystem on.  My 
embedded system is tiny (credit card size) so space is an issue.  I can 
not easily use a DiskOnChip as there are only 12 address lines from the 
CPU board connector available to me.  I am investigating serial flash 
devices.  Are there any that MTD or Linux supports ???

I know about the Atmel data flash devices.  Are they supported by Linux 
or MTD ???

I am interested in investigating the chipsets that the key ring type USB 
hard drives use.  Does anyone know what chipsets these are ?  Does MTD 
or Linux support them ???

Thanks for any advise, suggestion or pointers,
Brendan Simon.