Carry a photo of them with you:

For a beach wedding, a lei for those there in spirit 

A cigar or Wine Tribute

It is a celebration of that person as well as your day. If your loved one loved cigars, or wine, or something like that you can incorporate it like this.

A wedding Program mention is a nice idea:

And if you want to display photos of them, but in a more unique way, consider putting their photos in a mason jar display:

or this:

Anyone have any ideas to share on how they honored their deceased loved ones at their wedding?

(Source: zazzle.com)