Photographers both aspiring and expert will find this free online virtual lighting studio quite useful. The interface lets you add different lights with gells, softboxes etc at different angles and outputs what the effects of your positioning and modification would be. The ‘app’ looks like a great way to design lighting or even just see what the difference is between the effects of a bare bulb, soft box and a ring light.  The software is in Beta but works really well already. Give it a shot, try not to get mesmerised by the freaky blue eyed ‘model’ though…

Virtual Lighting Studio.