Idea 1: Write a small but romantic love letter (about 5 lines in length or less). Then, get your local newspaper and circle all the words you need (in order) to include in your letter. Then leave the paper with a special note on top telling him to put together the words to form the letter.
Idea 2: Write a line or two of a 20 -30 sentence love letter on bits of paper or index cards. Hide the cards in various places and leave a hint on where to find the next part of the letter. The really adventurous might try leaving bits of the letter around your city.
Idea 3: Tape a few hours of TV shows. Watch the shows and pick out words that have been said and create a love letter out of them. Then re-record only those words in the correct order to make a video love letter.
Idea 4: At set periodic times of the day send one line of an e-mail letter to your love.
Idea 5: On a plastic white or light colored plate, write a love letter creatively in permanent pen. Make dinner and leave the plate in place of your normal serving ware. (Make sure to switch it back before putting food on it.)
Idea 6: If your partner likes to read, leave a love letter in their book for them to stumble across.