I posed this a while back, but here is what I thought to include:
A 25-page document with pictures inserted (in Word) with captions with about 60 pictures total that has an outline narrative of our relationship.
Joint Lease
Joint bank account
Joint adoption for our dog (no kids...)
Joint travel: E-tickets and boarding passes
TONS of mail to our address together, including government, bank, phone, friends, cards to each other, bills, etc.
Phone Records shoring our correspondence the few times we were away and also when we were together
A big stack of Emails between the two of us
Print out of Facebook pages that say "in a relationship with.." - a lawyer told me to do this, no kidding!
My sponsor included a short one-page relationship narrative, too, where he talked about his feelings (mine was more choronological).
Plus a Cover Letter which includes a relationship narrative with names of friends/family met, etc. and when I came to canada, etc., plus a table of contents to all addendums.
We included TWO Statutory Declarations and two additional emails from friends/family supporting our relationship.
Hope this helps!