Best of the Web presentation I stopped to make the point that many apps and sites can work together even if they were not originally designed to do so. For example, I frequently share examples of using PicCollage and ThingLink together to create interactive multimedia collages. Greg Kulowiec calls this app smashing. You will find lots of examples of app smashing on Greg's blog.
Getting to the point that you can app smash requires becoming comfortable with a variety of apps and or sites. That doesn't happen overnight, it takes time. Set a goal of learning to use one new app or site per month in your classroom and before the end of the year you'll be ready to app smash. You can also enlist the help of your students to develop app smashes. Your students probably have favorite picture or video apps on their phones, ask them what they're using and then brainstorm possible uses of those apps for the next project in your classroom.