I use a SIIG 18-in-1 which is too big to take everywhere, but I just found the Kingston Travelmate, for $8. Look
here
for the reader. With a 1GB ordinary speed card it costs just $9 more.
I tested it. It's fast, but not the fastest available. I wrote almost 1GB of Leica DNG files to the Kingston card at 5 MB/sec, then downloaded them to a PC at 10 MB/sec. I put a SanDisk 1GB Extreme III card in it and it uploaded and downloaded at 12.5 MB/sec. It recognizes files on an SD card formatted in the M8. So no problems.
scott