1.) Buy (or, better yet, have printed on notecards that match your invitations), pre-made thank-you notes.
2.) If you think the pre-made thank-you notes are tacky, feel free to just use them as a form. Your guests don't actually want a heart-felt sentiment, they just want to know that you received their gift.
3.) The exception to this rule is gifts valued at less than $50 for a couple or $25 for a single person (or people who gave you a check for that amount.) You don't have to write them a note. They clearly didn't worry much about you.
4.) If there are still people who didn't get you a gift, go ahead and write them a note saying, "we must have missed your gift in the pile, but I'm sure it's lovely, and thank you." Or just write a note saying, "we loved seeing you at the wedding and our registry at Bed Bath & Beyond will expire soon." You can also be extra-sneaky, and send them a thank-you note for a gift they didn't give you, because then you will get a gift so that you can correct your error. Nobody is going to call you and say, "we didn't get you anything."
5.) If you exchanged their gift, be sure to explain what you exchanged it for. Everyone likes to know if what they got you is useful, so go ahead and tell them that it wasn't, but you got something that was.6.) If they got you something that isn't your style, or doesn't suit your house, and can't be returned, feel free to give it away or goodwill it and then tell them that it went to a good home, and you appreciate the thought but in the future they should stick to the registry. This will keep you from getting weird stuff for your baby.
7.) Feel free to have a few glasses of wine while you write the notes, and if you spill or make a mistake, just cross it out and write around the spill.
8.) If the person got really drunk at your wedding or behaved inappropriately, it's okay to scold them in the note and then mention at the end, "the KitchenAid almost makes up for your rotten behavior, so thanks, I guess."
9.) For late gifts, feel free to add a snide comment like, "I have heard that you get a year to give a gift, but I didn't think anyone actually followed that."
10.) For monetary gifts that are above the no-thank-you limit but still not enough to buy anything useful with, you should say in the note what the money is going towards, like "thanks for the check, we'll be putting it towards some new bath towels", so that you get your point across.
Does anybody else have some tips for thank-you notes? Feel free to share!