it just brings up all the new threads that appear in sections of PF that you said you were interested in most when you first joined. and yes it does fill up very quickly. you have to keep deleting if you wanna be up to date with stuff going on in translations, relationships, life in Poland etc, whatever you said that interests you. i haven't checked it since last year ;).
The checker thing is To tell you there have been new posts in threads you have.
nah, that's 'my threads'