I know this thread was meant to be to show your favourite 5, but mine keep changing! Yesterday I tripped over this extension in the Mo'zine forums. It's called
Forum Additive.
Basically, you enter your forum url and your nick and then all you have to do is right click the thread title (in the menu before you access the post) select Forum Additive in context menu and then select 'Monitor Thread' and then any time the thread changes, it notifies you! It also shows lots of data relating to the thread.
You Forum Freaks should take a look at this, it really is cool!
Tip. -
To add a profile, right click the addy bar and copy url, use Options on the ext in Ext Manager, select 'Forums Profiles' and then Add Profile. You'll get a little pop-up in text area and then just paste the url & enter your nick.