Computer-based instructional objects should be interesting to the students. I found countless examples where the math content was simply just skills based. I find it hard to believe that these would actively engage most students.
These particular types of educational resources are not dissimilar to other resources. There are examples that are short activities and there are long term projects that do exist. However, I found most of them to be created in the vein of a daily activity. There are some daily computer-based instructional objects that had merit, but unfortunately had too many broken links.
I did happen upon a Webquest that involve the creation of bridge, Don't Burn, Build. The activity was to take about two school weeks. I feel that the content of the assignment would prove to be more interesting to students than a skill building instructional object. This Webquest asked the students to do things individually and then collaborate in a group setting as well. There are links that are broken, but the bridge design project could be well done after finding new links. I really enjoyed the concept that the students would have to produce drawings and potentially a 3-D model of the bridge.
If you happen upon any exemplary up-to-date math Webquests, please point me in their direction. I just may not have been searching in the right locations.