I have used this for about 4 years now, brilliant piece of kit about size of a pack of cards.
http://www.kikatek.com/product_info.php?products_id=5990&source=froogle
Cost me £20 off Ebay brand new, not sure if you can still get them. I got the UK version, they also did a US version.
At OKW last month we ran 2 laptops, 1 netbook and an Ipad all together, no issues with speed.