If you have an unreliable internet connection that keeps going up and down this little webpage will let you know when it goes up or down.
It works best in browsers with tag support -- instead of just having visual feedback this page uses audio feedback so you can do something else until the internet comes back.
You can run this off the local apache or just as a file:/// webpage.
If you have problems running this off a direct file:/// prefix, you can setup a quick webserver using python by cd'ing into the directory then typing python -m SimpleHTTPServer. Another good option is to use the builtin osx apache in the sharing pane of System Preferences.