Celebrate your boyfriend by creating a playlist of significant songs. Making a selection of his favorite foods isn't technically free, but you may be able to do it with only the ingredients already in your kitchen. You can also write a heartfelt note or arrange a free activity, like a scavenger hunt.
Use your computer's software to craft a playlist of songs that your boyfriend can appreciate. Include only his favorites or use music that has been important in your relationship, like the song that was playing when you first met. Alternately, hunt down new bands and lesser-known songs that you think appeal to him. Ask musical friends for recommendations.
Treat him to a full day of his favorite foods. Prepare his favorite breakfast, lunch and dinner and make some tasty snacks too, or fill a book with handwritten recipes for all his favorite dishes.
Write your boyfriend a single letter that lists all your favorite things about him, or stretch out his birthday celebration by writing compliments and love notes on individual pieces of paper. Stuff them into a decorative container and tell him to pull out one note per day.
Hide notes around your home or neighborhood, and send him on a scavenger hunt to find them. Arrange for his friends to meet up at the last spot for a birthday picnic.