Today's post on Lifehacker showed how amazingly simple it is to make a parabolic reflector to increase your wifi device's antenna range. Just download a template from freeantennas.com and grab some tinfoil out of the kitchen and you will be amazed with the results.
I cut up an old manila legal file folder, wrapped it up in tinfoil and made a makeshift holder by stapling cardboard across the middle for the antenna to pass through in about 5 minutes and it boosted my signal significantly. I'm sure with some tweaking I could get better results but this was all I needed for my local network to function properly. Here are some screenshots of the signal strength in kismet:
Without the antenna:
With the antenna:
