Today’s idea is borrowed from: http://www.thesimpledollar.com/100-things-to-do-during-a-money-free-weekend/. Take some time and check out this site for 99 more ideas on things to do.
Learn the basics of a new topic. Just go to MIT’s OpenCourseWare, find a topic you’re interested in, download a bunch of mp3s of lectures on the topic, and listen to them while you’re doing household chores. Some great suggested starting points: microeconomics, macroeconomics, basics of philosophy, western philosophy, and introductory physics. Another great option: fire up iTunes, then click on the “iTunes U” option on the left hand side. You’ll find tons of material there to teach you the basics of countless topics.