Certainly a moment of silence or a candle lit in their honor, a table featuring old photos, or the powerful visual of saving an empty seat at the ceremony are beautiful gestures and keep those loved ones present in people's minds. You could include a tribute, anecdote, or anything about your loved one in your ceremony program, if you have programs printed. If you choose to do favors, you could consider a specific cause or favorite treat of the person you're missing. If they had a favorite drink, you could use it as a beverage greet or for toasting instead of champagne. Did your loved one wore a certain kind of cologne or perfume? You could consider wearing it, too, as scents are often powerfully connected to memories.
At this wedding featured on Style Me Pretty, the couple served cigars in honor of the bride's late father.