"I like your bag. Susan has a similar one, doesn't she?"
"________ _____ Susan, did she get the job?"
(changing the direction of a conversation but making a link to what has just been said)
by the way
"See you tomorrow. _____ ____ ______, how is your brother?" (changing the subject)
I went to bed late last night. ________, it was today at 2 am.
(additional information, usually surprising or unexpected)