Hm, but every time I reply to a thread, it gets added to my subscription list (which I enjoy, so I can follow up). So if I just mark one more (the one I want to remember to follow up with) as "subscribe", it won't stand out so I'll see it later. Know what I mean?
Option one = you can have multiple subscription folders. You can separate all threads to follow up with in a separate subscription folder.
Option two = you can stop automatically subscribing to threads you post in. Just use the subscribed threads feature for threads you want to follow up with. You can use the link at the bottom of the page to see all threads you posted in.