A while back, we were using zoneedit.com to keep track of changing DSL addresses at some of our offices. We had a little daemon running that checked the external IP every 15 minutes and shoulder-tapped zoneedit if there was a change. It started failing after a while, and we discovered the external server we were using to query our IP was wigging out.

So we googled for some alternatives. None were much good. So we wrote two of our own, one hosted at the company's main site and one at a free Google App Engine site. That was a good move, as both mostly outperform the various freebies out there.

Along the way, I wrote a little script to test a bunch of alternative IP sources. Just for fun, I added a version of your Google query to the mix, along with the OP's site, and just reran it, with the following results:

  $ ip all
      IP Address   Time  Bytes Server
  [cynwoody's IP] 0.217     58 dynamic.zoneedit.com/checkip.html
     192.168.1.1  0.197  25545 www.whatismyip.com/
  [cynwoody's IP] 0.497   7382 whatismyipaddress.com/
  [cynwoody's IP] 0.144  13010 www.hostip.info/
  [cynwoody's IP] 0.131   9007 www.ip-adress.com/
  [cynwoody's IP] 0.577  14706 ip-lookup.net/
  [cynwoody's IP] 0.426  20508 www.geobytes.com/IpLocator.htm?GetLocation
  [cynwoody's IP] 0.492  10054 www.melissadata.com/lookups/iplocation.asp
  [cynwoody's IP] 0.917  22058 www.dnsstuff.com/
    end of file   0.120      0 www.ipaddressworld.com/
         1.7.0.0  0.486  18427 www.ip2location.com/
  [cynwoody's IP] 0.191  34468 www.find-ip-address.org/
  [cynwoody's IP] 0.221  25019 www.iplocation.net/
  [cynwoody's IP] 1.040  10776 www.lawrencegoetz.com/programs/ipinfo/
                  0.272      0 www.ostrosoft.com/OIT/external_ip.asp
    66.249.74.77  0.576  32953 www.google.com/search?q=my+ip
  [cynwoody's IP] 0.074   1467 internetaddress.me
  [cynwoody's IP] 0.097     35 www.[cynwoody's company].com/ipaddress.php
  [cynwoody's IP] 0.110     35 [cynwoody's app].appspot.com/ipAddress
  $

The Google hack got the wrong IP. I assume the reason is that script is downloading the page and parsing out the first thing that looks like an IP address it comes across, but the part of the Google response that shows your IP bold and clear occurs further down in the result. So, it could be made to work, but would require a less trivial parse.

BTW, FWIW, www.[cynwoody's company].com is hosted at FutureQuest. Attaboy FutureQuest!

And internetaddress.me did best of all, responding in only 74 ms (I'm located in the Boston area), but one has to wonder what popularity will do.