I don't want to see an ad on my desktop that I already blocked on my laptop.

So, I sync my adblock files together and run them off of a subscription.

Setup:
Server
Laptop
Desktop

Laptop and Desktop send their ~/.mozilla/firefox/*.default/adblockplus/patterns.ini 
to a user account on Server. Server does a minimal amount of work to sort and 
double-check the Laptop patterns.ini vs the Desktop patterns.ini vs the Master 
patterns.ini to make sure they're not wasting space with multiple lines of the 
same block. Then we assemble all three together to create one big file which will 
end up being served by our subscription. Then we subscribe and everytime adblockplus 
syncs to the subscription, your blocks from your laptop and desktop will now be used 
on all of your machines.

This process is rather easy, but can seem cumbersome. As with anything, if you have 
an easier method to accomplish this, please notify me at dayid@dayid.org

Step 1: We're going to skip installing adblockplus as we're hoping that anyone 
        wanting to know how to sync adblock plus already knows how to get it running 
        on their firefox.

Step 2: Configure a passwordless ssh key to pass from your user on Laptop and Desktop 
        for them to login to Server.

Step 3: Write a script to rsync the patterns.ini from Laptop and Desktop to Server 
        at your chosen interval.

Step 4: Run this script in cron.

Step 5: Write a script to diff/combine all of your different machine's files into 
        one master.

Step 6: Publish that master file to a web-available location.

Step 7: Add that master file as a subscription in your adblock preferences.



================================================

Step 1: Setup adblock on all machines, and block things with it.

Step 2: On each machine:
        user@Laptop$ ssh-keygen -t rsa
                     (No pass)
        user@Laptop$ scp ~/.ssh/id_rsa.pub user@Server:/usr/home/user/.ssh/user.Laptop.pub

        After that is done for each machine:
        user@Server$ cd .ssh
        user@Server$ cat user.*.pub >> authorized_keys
        user@Server$ chmod 400 authorized_keys

Step 3: On each machine:
        (obviously changed the output ads.laptop.txt for each machine to a uniq name)
        user@Laptop$ echo "#!/bin/sh
                     rsync -cz /usr/home/user/.mozilla/firefox/*.default/adblockplus/patterns.ini user@Server:/usr/home/user/ads.laptop.txt" > adblock.sh

Step 4: 
        user@Laptop$ crontab -e
                     15 */2 * * * /bin/sh ~/adblock.sh > /dev/null 2>&1
        (Changing the time to as you choose, the above will sync every other hour 15 minutes into the hour)

Step 5: user@Server$ vi adblock.sh
        #!/bin/sh
        for URL in `awk -F "http" '{ print $2 }' ads.*.txt`
            do echo "http${URL}" >> $$
            done \
        && sort $$ | uniq > adblock.txt
        -- Add this part to a cronjob also: 20 */2 * * *  /bin/sh ~/adblock.sh > /dev/null 2>&1

Step 6: user@Server$ echo "mv adblock.txt ~/public_html/" >> adblock.sh
        
Step 7: Firefox/Tools/Add-Ons/Adblock Plus/Options/Filters/Add Filter Subscription/Add a different subscription
        Filter list location: wherever you published it on the web. 
        YES Update automatically
        YES Enable filters