Weddingbee boards

My father died a few years ago, and I had my husband wear my mother's first gift to my father (a ring with a sapphire) as a twist on the 'something blue' tradition.  We also had lots of pictures on display.  I've seen other types of tributes - carrying a mini photo of a loved one in your bouquet (you can get someone to make one for you on etsy), or a special note in the ceremony program, or a special song or mention during the reception.  I think it really depends on the personality of the loved one and how your FI would best like to remember him.