Summer activities aka mom I'm bored.

I'm not homeschooling yet, but since the kids are bored, I told my daughter to make a calendar and then we will fill in the days with interesting activities. Everyone gets to input. They are already signed up for the summer library reading program, so that will be something they do quite often as well as swimming but for the rest of the time we need to brainstorm. One idea I've already included is homemade ice cream http://crafts.kaboose.com/ice-cream-in-a-bag.html. I also plan to have an insect day to try to learn the names of different insects and also try to incorporate the stories in the quran about insects. I've also borrowed a stack of books from the library with activity ideas that we will go through. The kids would like to try going to different parks than the ones they usually go to and having a picnic which they love to prepare themselves. They also want to have school friends over. For jumuah I would like to have prayers outdoors with my son as the imam and he can give a khutbah (sermon) since the masjid (mosque) is quite a ways from us as there is none where we live. A scavenger hunt will be done again this year like last year too. So what kind of frugal ways are you using to keep your kids busy this summer?