While it's theoretically possible, I'm not sure whether this is practical for general use on a LAN. You'd probably have to have a wireless antenna poking out of your laptop, which you'd point at the access point. Seems a little bit inconvenient.
You don't need to point the antenna at anything; you can use multiple antennas that steer the beam ("beamforming") in a desired direction. Link:
http://en.wikipedia.org/wiki/Smart_antenna
Basically you can have a "phased array" of N antennas (2 counts as an array, but you can think of a line of say N=8 antennas) that delay their broadcasts relative to each other in such a way that the N signals interfere constructively along some directions and destructively along other directions. This is because, from far away,
cos(angle_from_line_of_antenna_array) = const*propagation_delay_between_antennas