As a couple in our late 20s who have been living together for more than a year, my fiancé and I have all our household necessities and are not inclined to set up a conventional registry. What we could really use is money for a down payment on a house. Is there a tactful way to get the word out that we'd prefer cash?
The tried-and-true method of telling people what you'd like is word of mouth. It's a good idea for couples to provide their parents, their attendants and those close to them with a list of registry sources or, as in your case, let them know cash is preferable. But remember that there's no dictating to guests what they must give; it's their prerogative to choose. If you're asked directly, be honest and polite: Say, "We're saving for a down payment on a house, so if you'd like to give a check, that's how we'll use it. But whatever you decide will be terrific. Thank you for thinking of us." Cash presents are perfectly acceptable - as long as the guests feel comfortable with the idea. Some people just don't like giving money, and that's OK. For this reason it's a good idea to set up a traditional registry too - even if it has only a few items on it - so guests have a sense of what you like and need.
Here are some suggestions for other new-age traditions.