You know, I hate to be a sourpuss, but for me, really none of them are memorable. As I am writing this I can only think of one...a "love songs" CD with a photo of the couple, reclined and looking all romantic. I guess that one I remember because it was corny to me and, I mean really, was I expected to listen to the CD on a regular basis?
What I have found and actually, I appreciate, is that more and more weddings have no favors at all! I always feel sort of guilty when I find myself at a wedding and feel the urge to either ignore the favor completely or take it home and stash it somewhere for years, feeling again guilty if I toss it. I feel so guilt-less when I just don't even have to think about it.
A great ceremony, lovely exchanging of words, seeing a beautiful bride and groom, decent food, and great dancing is more than enough for me, really. My favorite part of weddings for me is always that moment when the bride and groom see each other for the first time -- always brings a little tear! I just love that. I feel favors are just not necessary.