Buckyballs are my favorite desk toy. For about $34.95 (a little pricey, but worth it if you can afford it), you get 216 little magnetic balls which you can squish, pull, wrap around your finger, or make into neat shapes. Their sleek metallic appearance fits in even in really conservative office environments, and they come with a nice little transparent cube carrying case.
My favorite thing to do with these is to hold two chains of buckyballs near to each other and feel the magnetic force pulling them together. I also like to squish them around; they make a very satisfying clicking noise. I’ve also figured out how to make a sphere, a cube, and even a companion cube-type shape.
Please keep in mind that these are NOT for small children or anyone else who might inadvertently swallow them (such as an adult with a tendency to absent-mindedly put things in their mouth). Swallowed magnets will send you to the ER.
Pros: shiny, clicky, addictive, appropriate for almost any office environments, and can be used at varying attention levels (from absent-mindedly squishing them to making them into complex shapes).
Cons: Expensive, not safe for small children, and probably not great to keep around electronics (I’m constantly accidentally putting them next to my phone or iPod; hasn’t killed them yet though).
Overall: Five stars. I love these things!