Should we give cash or buy something off their registry?

It's completely acceptable to give cash gifts, or even gift cards at weddings. Their should be a box or bird cage or w/e they choose for those types of gifts there. I'm getting married in 6 months, and the stuff you register for are supposed to be like your "dream wish list" if you get them cool, of not no biggie! lol I'd prefer cash to be able to put towardsna downpayment on a house, but most people like to know what they got you. Personal choice, either would be more than appreciated! :)