if you've ever thought about building your own PC from scratch then one thing you'll have to get familiar with is circuitry design?
DipTrace is a professional tool that's not exactly easy for those that have not got much electronic know how but it does produce stunning results. DipTrace allows you to import projects and libraries such as LT Spice, CAD, Accel, Allegro, Mentor, Protel among many others so professionals will find this a really useful complementary tool to their existing toolbox. Creating projects is simple - it just requires dragging and dropping of all the components you need into the work area and then you subsequently make connections between pins to create your own circuit. If you're not sure whether your circuit will work, there is a useful validator which checks whether what you've built will actually work in the real world. If you have gone wrong, DipTrace can suggest how it can be fixed or even automatically shift components into the right position which is where this program excels where others fail.
A professional PCB design program that is not for the faint hearted but will be a delight for professional designers and electronic engineers.