I just received my USB asic Scrypt miner and have been playing around with it mining various Scrypt coins including litecoin. Stock setting get you around 3mh/s to about 4mhs depending on your setting in bfgminer.
It works with a powered usb hub on windows, linux or mac along with devices such as a low power Rpi as long as you use the powered USB hub. You can overclock up to 6 mhs but I prefer to stay in the stock 3-4 mhs range as overclocking requires more cooling from other fans.
If you mine for a hobby and are not concerned about ROI, this is a great little device that uses less than 8 watts at full force. Some people also use them as a lottery device to try and solo mine a coin they like such as Litecoin. The chances you will get a block solo with this are slim, but that is what makes it fun.