The first is my own script over at Cable Modem Check, which I wrote to use X10 modules to stop/restart my cable modem when there's a problem.

The second is a program I use called "Downtime". This is a Perl script, freely modifiable, that monitors one or more connections and tracks the downtime. I modified my copy to replace the Cable Modem Check and to do several other things in the office; it's extremely well written and documented, and very easy to modify for any purpose.