I am currently constructing a virtual webquest for course EDX 3280. Initially, after selecting my curriculum standards and the general direction I wanted the lesson to go, I set about finding a few quality resources. I think that finding engaging, instructional and age appropriate resources are essential to an effective webquest. Many resources that I have considered are engaging and colourful, however the games are rarely concept based. Instead, mathematical games tend to focus on the skills of the concepts. Such games would more effective helping students consolidate learning, after students have already discovered strategies and skills for themselves.
If you are focusing on shape for your webquest, I found a fantastic resource for creating virtual geometric shapes. The site allows students to create any geometric shape they could imagine, using tools to label sides, faces or vertices.
Check out the resource at Geogebra!