Toys made of paper. Some are based on the Origami craft, others are more complex and have moving parts.
There are even some projects for papercraft automata. Good for all ages!
Paper Foldables
Here you have a good selectiong of ready to print and fold papercraft templates. They are in PDF format, most seem to fit on a single page. There aren't much description but I don't think you need anyway.
How To Make Paper Craft Model From Scratch
A very funny papercraft toy. But the instructable isn't just about it, it show also how to use 3D software to build youw own model. Advanced stuff.
Click here to view the instructable
Click here to view the instructable
Paper Crafts
This site has a large number of guides for papercraft toys. Most are good for little kids.
How to Create Your Own Custom Papercraft Toy
A simple papercraft toy with your custom drawings. Very easy to follow by How To Geek.
Follow this link
Paper Toys
This site publishes plenty of papercraft patterns and links. Not all of them are good but the content is frequently updated.
Animated Mechanical and Optical Illusion Paper Toys
Rich collection of papercraft toys. Optical illusion toys, automata, cams and cranks - all made (mostly) of paper.
Oscillating Woodpecker
This is maybe the easiest way to make an oscilating toy. I guess it wouldn't take more than a hour to build and is cool enough for kids to do.
See the instructable.
See the instructable.