"If you went to a wedding and the couple didn't register anywhere, should we give a gift that they'll remember?"

When we got married, we didn't register.  First, we weren't concerned about gifts, we were just excited to be able to share the day with our friends and family.  Also, when it came to gifts, if someone wanted to give us a gift, I wanted it to be something that they wanted to give us.  We received wonderful, thoughtful, unique gifts that when I see them today (almost 15 years later) it makes me smile when I think of our wedding day and the special person(s) that gave us the gift.  Here our some of the things we received and also some other ideas.

Our invitation was professionally framed with dried flowers.

Homemade Christmas decorations for our tree for years to come.

Items with our names and date inscribed, like a mirror or clock.

Personallized plaque for our home with our last name "The _______'s"

Picnic basket with everything (except the food) for a picnic for two.

Beautiful vase or glass sculpture

Monogrammed travel/toiletry bags from LLBean or someplace like that

A blanket or pillow with a personal inscription or favorite poem embroidered on it

Handmade pottery or servicing dishes

Think about the couple and their interests or what has a special meaning to them and you and go from there.

A lot of people who are getting married a second time, or who have been living together a long time, or who are adults and have lived alone for a while, don't really need more things.  Find out what their favorite non-profit is and give a donation on their behalf.  Bonus points if you can find something like the art theater I work at that will display their name on a seat forever for $300.  That way they can be reminded of it every time they visit a place they love, they don't have one more thing in the house, and they feel like they're supporting (through you) something they really love.

If you were only looking to give a little gift, scrounge up people you know who will be at the wedding who own video cameras.  Have everyone record and give you the tapes, then edit them up a home made wedding video.  It's  a tough one if you don't have the tools and know-how, but I know you're a smart guy with resources, so you might be able to pull it off!