these lovely little bike lights by copenhagen parts attach to the bike with magnets, which is also what turns them on! available with either a polished aluminium shell or a silicone rubber case (in a range of colours), they are extremely minimal indeed.
using the steel frame of the bike not only as a means of attaching but to complete the circuit is a great idea, meaning there is no need for an on/off button. although maybe not quite as versatile as a knog or bookman light, it can still attach in the right places on your bike (as long as it it steel!). i thought those previous two lights were quick to remove but these would be even quicker, and (unless you've got some steel tube in your bag) much less likely to accidentally turn on.
i've posted about copenhagen parts' bike porter handlebars before, which looked like a great product. these lights, released in autumn, look like they might be even better!
via moco mr