Nick,
I checked your account and you have a 168 subscriptions to individual threads. To not get notifications on these you can individually deselect specific threads in your control panel under "Subscribed Threads" and then "List Subscriptions".
We're considering having threads automatically close after they do not have a post for a certain amount of time (say 60-90 days). This would eliminate the possibility for everyone to get notifications from a really old thread since in effect it would be closed for posting unless a mod opened the particular discussion.