Proxim has some nice ones, the Airport (Apple) looks promising. They all offer 10mps transfer speed.
I have an Acer warplink that maxes out at 1mps...not so hot. But it is good enought to transfer files from the house to the driveway.
There are a few others, but they are all expensive if you want speed... a hundred or so per card.
Also the longer the distance the slower the speed. Probably the longest distance you can normally get is a 100 feet or so.