My nexus 7 was dropping WiFi at home. It would connect, working for maybe a minute or two, then disconnect. This is a know problem with some nexus devices. However, at other locations my WiFi works fine.
I looked at the settings of my router. remembering that sometimes handheld devices don't play nice with certain configurations of WiFi.
One thing I noticed was that the router was on Channel 3. Typically if you do a scan with some sort of WiFi analyzer is that channel 6 is the common/default ap channel. I changed it to it, restarted the thing, and my Nexus has yet to drop it signal.