Most modern couples make it easy for you to pick out a wedding gift (thank you, wedding registries). But if you're going to disregard the preferred gift list, what you give has to be good. And you're in luck—because some of those gifts won't cost you a thing.

1. BONUS GIFT CARDS

Gift cards and cash are great gifts because they let couples enjoy a nice dinner out or pick up household needs that didn't make it onto the registry. But how do you get them without doling out greenbacks? Look for gift card deals and bonuses at places you already shop or dine (so long as it's a place the couple might also enjoy). In many cases, restaurants and stores will run promotions that give you free gift cards when you buy a pre-determined amount of gift cards. Stores such as Kohl's, Target, and Bed Bath & Beyond have all run similar promotions (and are also popular wedding registry destinations). If it's a store you already visit frequently, you can purchase gift cards to shop for everyday expenses, then wrap up the free bonus gift cards as wedding gifts.

2. FAMILY HEIRLOOMS

Weddings are the perfect time to pass on a family treasure. In most cases, these gifts don't cost a thing (except if it is in need of repair, restoration, or cleaning), but that doesn't make them cheap. In fact, marketing professor Utpal Dholakia suggests that heirlooms, like grandma's wedding ring, have more worth than a pricey crystal picture frame or kitchen appliance because of the emotional connection and significance that the item holds.

3. THE CLASSIC REGIFT

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Regifting is never quite ideal, but in the right scenario, it’s not such a faux pas, especially if it’s an item the couple really needs or wants. But before you go digging through your closet or basement for the "perfect" wedding regift, you'll need to consider Emily Post's rules for appropriately passing on a present. The recycled gift shouldn't be personalized or handmade, should be brand new in original packaging, and something that the couple really would like. Oh, and don’t rewrap a gift that they gave you in the first place. That's just tacky.

4. WEDDING PREPARATION HELP

If you have useful wedding-prep skills, it might be worth exchanging some hard work in place of a wedding gift. In most cases, brides and grooms are stressed about the final cost of their big day (the national average came in around $35,000 last year) , but if your skills—such as floral design, dress alterations, or invitation design—can lower the cost, they'll likely be happier getting your help instead of a coffee maker. Of course, you'll have to work out the details in advance, but then again, that's one less gift you'll have to haul to the reception.

5. THE GIFT OF TRAVEL

Honeymoon registries have become a popular alternative to dishtowels and potholders. If you want to go for Guest of the Year, you can one-up the cash gift with airline miles. Instead of cashing in your unused miles or points for magazines, opt for gift flights or hotel stays instead. With some airlines, it’s cheaper to purchase tickets for the couple outright (avoiding mile transfer fees), so confer with them before the big day to make this gift come true. And don’t forget the important travel rule for the newly married: always use given names on tickets and any bookings that require matching ID, since any potential name-change paperwork won't be filed until after the happy couple gets home.

6. PET SITTING

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Wedding planning is hectic and expensive, so help your favorite couple stress (and spend) a little less when it comes to making all of their final arrangements for their pets. Well in advance of the big day, offer to pet-sit when they leave town for their honeymoon—they're sure to stress less if they know the daily dog walking, mealtimes, and kitty cuddles are being attended to by a friend. But before you jump in, make sure you're a good match with the couple's beloved pet; putting high-energy pets in a low-energy environment, for example, won't make for a compatible (or enjoyable) experience.

7. CASH-BACK GIFT BUYING

You can use this hack to purchase something the couple has their hearts set on, and it still won’t cost you a dime. If your bank account or credit card offers cash-back on purchases, plan in advance to save up the rewards from everyday purchases to put toward a wedding gift. While you're technically exchanging money for a gift here, it's the equivalent of using a free gift card to pick up that wedding present. Some credit card companies even offer the option to put cash-back rewards toward discounted gift cards, which also works for stores the couple frequents.

8. HONEYMOON HOUSESITTING

Being away from home for an extended period of time can make anyone nervous, so ease the couple’s worries by offering to housesit while they drink margaritas on a tropical beach. Depending on their digs, you may be in charge of everything from picking up the mail on a daily stop-in to actually spending the night while caring for pets and plants. While this gift is free for you, it’s a big budget saver for brides and grooms: on average, housesitting can cost between $25 and $50 per day.

9. PRO-BONO SERVICES

If you're an accountant, lawyer, or have some other kind of professional specialty or skill, consider giving free services as a wedding gift. You can offer to help the couple through the name change process, write their joint will or prenup, give them financial advice, or even just give them a couple of months worth of haircuts (but only if you're a professional stylist—we don't recommend this for just anyone with a pair of scissors and a trimmer!). You can create a gift certificate and deliver it with a card on the wedding day, and follow up afterward to see when they'd like to schedule an appointment (but note: if they decline your services because they already have a financial advisor, for example, then you need to graciously congratulate them again and send a gift).

10. SOMETHING GREEN

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Thinking of a gift for a green-thumbed couple? Consider sharing your favorite plant or a starter garden kit. If you're already a gardener, you can compile seeds from your existing stash, get seedlings growing, or transplant a portion of your favorite plant into a new pot. Just remember that this gift needs to be delivered after the wedding, avoiding the chance that the couple comes home to dead plants.

11. POST-HONEYMOON MEALS

Getting back into the flow of everyday life is a little strange after such a big event, so help the couple out by stocking their freezer with post-honeymoon meals. You can host a meal-making shower in lieu of a bridal shower, getting other friends and family (and their specialty recipes) in on the gift. Even better, consider coordinating with their honeymoon housesitter to drop off some early freezer meals that the couple will have ready for when they get home jetlagged. Chances are, they'll really appreciate the thoughtfulness of your gift—which is really the best kind of gift to give, regardless of cost.