On a related note, I live in a high rise condo in Milwaukee.  There are a ton of hotspots.  I left mine wide open, in the spirit of sharing.
The other night I was having bad problems with speed.  My connection was up and down as well.  I decided to look into it, and I had 12 freeloaders on my WAP.  I decided to kick them off go to WPA encryption.  Speed and connections are both looking up.