There are many unsolved in mathematics. Some prominent outstanding unsolved problems (as well as some which are not necessarily so well known) include
This Instructable will walk you through building a medium sized Tesla coil.
Ther 18 most suppressed inventions ever are reviewed in this truTV photo gallery
Simple animation to explain complex principles - Electronics Scraps at Hiox.org, The technical and non-technical information Sharing Resource.
Tel-Aviv University demos quantum superconductors locked in a magnetic field....watch video.