Reader Rob P. uses Firefox quick search bookmark to see if web servers aren't reachable. He says:
Add this as a Bookmark in Firefox:
I have its keyword as "ping" ... so all I have to do is type ping google.com in the address bar.
The advantage of pinging a server using a webapp versus from your own command line is that you can see whether or not your network connection is the problem. This looks like a good alternative to sites like DownForEveryoneOrJustMe.com, though a bit more geared towards networking geeks. Thanks, Rob P.!