One thing I haven't seen mentioned on this site is a large poster sized certificate as a guest book alternative. Drawing from my Quaker upbringing we are incorporating one into our wedding. Typically they are very artistically done and say something like:
"On this day the first of January of the year two thousand So-and-so and So-and-so took each other by the hand and exchanged the following vow:
"In the presence of the God and of this assembly, I, take you to be my patner, promising with Divine Assistance to be unto you a loving and faithful spouse until death shall separate us.
"As confirmation and celebration of this comitment we set our hand below (signatures)
"And, we as members of their loving community, having been present in caring witness of this union and promising to honor and support their unity, set our hands below (guest signatures and comments)"
But you could adapt the idea and put just about anything you want.
You then hang it in a prominent place in your home so it can constantly remind you of your vows and the community you shared them with.
We like it and are getting a 52"x52" variation of the certificate printed for guest to put their comments and remarks, well wishes etc. as they move from the ceremony to the reception.
-- Anne