I've had a revelation lately about the value of thank-you letters; it all started when a friend of mine sent me a thank-you for having him to a family gathering on the 4th of July. (I know it wasn't really lately but it's close enough) It wasn't as if he didn't thank me at the time, but the letter added a nice personal touch that most people don't think of. There is just something about receiving a letter in the 'ol snail mail that is still special (but that's a whole other topic), and no matter how many times they thank you, or you thank them, it isn't as powerful as a letter after the fact. Consequently I've decided to take up the habit also, because I want people to know how much I truly appreciate them.