I found Try Engineering looking for some fun interactive games for my kids on the web. The site is for people interested in engineering careers and so has a lot of information about careers and schools.
Two tabs are of interest in our house. One is the Lesson Plans tab that has a long list of interesting engineering activities for either homeschool or co-op. You can download an 8 page pdf catalogue of all the available plans. The other is the Play Games tab. They have 4 interactive activities produced by the site--Bionic Arm Design Challenge, Questioneering, Design a Parachute, and PowerUp. They also have a good-sized list of other interesting engineering games. I showed this to Ds#2 just before he went to bed and now he can't wait to get on the computer in the morning!