If you use DynDNS, you can grab the
official app from the Market. Make sure to go to dyndns.com and make yourself a hostname. Then open the app on your phone, enter the appropriate information (in this case make sure to check update wireless), forward the proper port on your router, and enjoy.
I got all excited when I saw this question, but my hopes and dreams crashed down when I found that I couldn't start AirDroid on a 3G connection
(
Oh, well, there are other things to play with when it comes to Dynamic DNS