If you made plans for your weekend, you might want to kiss them goodbye. Apple yesterday released its iTunes Rewind 2011 list, with the 40 top iPhone and iPad apps of the year. The iTunes store now has more than 500,000 apps in it, but this year’s top apps list shows that fun is the dominant theme. Games and social networking tools dominated, and photo sharing tool Instagram was chosen as the No. 1 app of the year.