I really liked, (and miss! -I try to find it all the time) the 'set comeback message' feature' -I can't remember the last version it was in, but I think it's not been around since Windows Live Messenger came about, Offline Messeges/ing negating it's function somewhat.
...but I miss it!
Also, I think we used to be able to set custom statuses for every status, from Online to out to Lunch to Away. I like it silent when I'm set to Busy, but I'd like to be able to set a custom status s.a. studying etc while set to Online/when I'm occupied or whatever but want to be able to hear MSN; so I don't have to change my settings everytime I want to change status.
I think that'ld be great