Don't send thank-you notes. Send a short note with an update.
Dear Uncle Joe and Aunt Jane:
I was thinking the other day about our wedding, and what a wonderful time is was. We were so glad you were able to be there. Married life is really great--in so many subtle ways. I thought I'd let you know that we used the money you gave us to finally buy a sofa, and we think of you often when we sit on it in exhaustion after the workday. Thank you so much for that gift--it has really added to our home.
I hope you both are well, and we look forward to seeing you at the BBQ on the Fourth.
Something like that. But get them out now, before it's a whole year.
And when your friends are planning their weddings, add your voice to the chorus of etiquette experts that says do *not not not* wait until you get the pictures to write the notes. Nobody cares about the pictures; they care about the notes.
(OK, OK, some people care about the pictures, but most people took them on the cell phones anyway, or they can download them from Facebook if you post them there, so just write the note.)