Other than the four-slot SD card reader, Elecom also releases the MR-SMC06 microSD/SDHC memory card reader with two card slots. The reader looks like a USB flash drive and uses USB 2.0 interface. It supports TransFlash, microSD, and microSDHC Class 2/4/6 up to 32GB.
The Elecom MR-SMC06 costs 1400 Yen and is available in black and white.