When I was growing up, I had to write a thank you note for any gift or good gesture received. These days appear to be long gone, but I recently had a note dropped on my desk for a job well done. Not only did I feel genuinely appreciated, but the realisation that these traditional values do have a place in the modern world was immensely reassuring.
So in business or at home, a handwritten thank you note can make a world of difference. Be as creative, modern, stylish <insert any word that describes you best> as you want to be, but do put the effort in.
Please do not try to modernise this tradition, it only works with hand written notes, emails do not qualify as thank you notes and certainly does not demonstrate the effort that makes the hand written thank you note so worthwhile.