Is there a website that tells you what to write in thank you's?

There is...i just don't remember it. sometimes, you can google how to write a thank you note. also, there is a book in b&n or borders called something like the brides book to writing thank you notes.
some tips: be sincere. mention the gift and say how you will use it. don't say thank you for the gift and sign your name. make it personal!!! even if you hate the gift, never let it come across.