Read a book that your eyes haven't seen since pilot school, network with other pilots, go "split" some time with a pilot friend and add to your Actual Instrument and Cross Country time or go to a free aviation seminar. Find some interesting seminar topics on the AOPA site or the FAA site, find their Events List here. Most recently they presented a seminar titled "iPad in the cockpit". By the way if you haven't subscribed to Fore Flight, do yourself a favor and look into this super helpful ap.
