You may have already seen this on other hardware hack sites, or on Screensavers, but in case you haven’t, this is an extremely easy and quick-to-make parabolic reflector that can be used to direct the signal on your wireless (WiFi) antenna and to boost its gain (betweenb 10 and 12db). Definitely worth trying before investing in a larger commercial antenna. You can make the reflectors and mounts out of scrounged material, such as cardboard and wire mesh, or even cut-open Pringles cans.
Hardware Beyond the Hype