Classic-to-USB interface

I remember at one time I found a company making a device which allowed you to access files on an attached USB mass storage device (thumb drive, hard drive etc) from anything with a serial (async or spi) interface - it would even do the filesystem crunching for you (FAT only). Intended for embedded applications (such as data loggers) but I thought it'd be great for old computers... Unfortunately, a quick google did not turn up the device, and I can't remember the name (otherwise it'd be tooo easy of course!) I found that in general todays embedded chips have features very similar to what used to be in full-sized home computers - thus all the peripherals for those interface quite nicely to the old stuff! (well, except for some of the 3.3V/5V issues...) Joe.