I recently switched DSL providers from Telocity to COFS.NET. The service so far has been an order of magnitude better than Telocity's and the connection has been mostly consistent.

With one exception.... Every few days the DSL modem would drop connectivity. A reboot would always fix the problem, but this didn't help me if I was not onsite or could not convince a family member to brave the server room and reboot the modem. Though I could dial in to my PPP server, rebooting the router/firewall would not help.

I posted a question on flux asking for suggestions. The best solution turned out to be a ttyS0 controlled X10 module that could bounce power to the modem. The Radio Shack parts are as follows:

Grab the heyu Software to control the units from Linux. Because the site is sometimes down, I've archived a copy here. To build, cd to the heyu.dir directory, the run Configure and make.

A sample .x10config file follows below. Place it in the home directory of the user ID that will be used to reboot the modem. This does not need to be the root user if the un-privileged ID has read/write access to the serial port. 

     modem		A 1
     #
     # set default housecode -- the one the switches will use
     HOUSECODE	A
     #
     # Set the port the program will use.
     TTY		/dev/ttyS0
     # The NEWFORMAT directive allows version 1.28 and higher to display more
     # informative messages.
     NEWFORMAT
     # The file listed with MACROXREF is where HEYU will store the addresses
     # where macros are loaded in the CM11A.  If you don't use this directive,
     # The macros addresses will not be cross-referenced.
     MACROXREF       .x10macroxref

I added the following entry to root's crontab: 

  */5 * * * * /root/bin/watch_cofs 2>/dev/null
The watch_cofs script is: 
  #!/bin/bash  
  STATUS=`ping -c 2 -q 216.4.122.128 2>/dev/null`
  CODE=$?

  NOW=`date`
  if [ $CODE -gt 0 ]; then
  	echo $NOW DOWN >> ~/temp/status
	/root/bin/heyu turn A1 off
	sleep 15s
	/root/bin/heyu turn A1 on
  else
        echo $NOW UP   >> ~/temp/status
  fi

Place the script and heyu binary in an accessible path. Note that the PATH variables are not always defined when the CRON executes. For this reason, it's safest to put the entire path to the heyu binary. The above script will log the UP/DOWN times into a status file. Make sure to change the IP address to an IP that *should* be available when your Internet connection is active. A good choice is often the primary or secondary nameservers of your ISP.

If you are moderately proficient with scripting, you could also choose to do several tests and only if all fail do you reboot. I'll leave this as an exercise for the reader :D.

Connect the Home Control Center to the controlling computer via the serial cable. Plug the modem into the Appliance Remote Control Module. These do not need to be the same machines, but the control PC must be on continuously.

Someone else has also done this:
http://ralf.alfray.com/photos/Misc/DSL-X10/