Bad router? Does your computer connect to it via Wi-Fi? Did you set your router to not broadcast the SSID? My router needs to be powered down every once in a while for it to send Wireless signals.
There are lots of other threads about this, but aside from the good points that weirdkid makes, you might also see if your router is broadcasting in 802.11n or a only, since the Droid doesn't support either of those.
well buddy i had the same problem, i have a linksys N router so what i did was to change the settings of the router to b/g/n you can do it if you have the same problem.