Crystal growing (sheep / garden)
Elastic band gun.
Domino toppling.
Levitron.
Solar charging (magic) night light (sunshine jar)
Glow in the dark stars and star map.
Paper hot air balloon.
Gyroscope.
Ant farm (see thru gel)
Plant growing (hydroponics)
Knitting.
Skeleton kit.
I'm surprised this option is missing given the audience. I'm currently programming a compute intense application.. every time I test it I can feel the heat from the laptop rise.
Am I missing something but if you are at home couldn't you use your telephone (the one with the broadband) or use VOIP. Why would you use your cell over your own infrastructure and let vodafone charge you for doing so. Now if you got a discount for making calls via the femtocell i.e. you got a discounted rate when at home then (if the price was right) you could use your cell all the time and not the house phone.