Having Fun for (almost) Free

Living within your means (*gasp*) does not mean a life without fun and excitement. I personally feel that instead of looking forward to a few big experiences of fun each year (e.g. vacations, holidays) we should build a little fun and relaxation into each day -- or at least each week.
Here are some ideas off of the top of my head on how I enjoy life for free or very low cost:

• Play guitar
• Read a book (from the library)
• Watch a movie (from the library, or Netflix is cheap)
• Talk to my friends on the phone (or use Skype)
• Have friends over for a BBQ or a drink
• Jog around the park or lake
• Go to the gym (only $10/month for me)
• Play a board or video game with my sons
• Go to the park with my kids and play catch
• Go to the bookstore and browse
• (but not if you can't help yourself from buying books!)
• Ride my bike
• Go geocaching
• Volunteer
• Facebook
• Play music
• [ * censored * ]

What do you do for (Free) fun?