Questions often get asked 'how did you light the subject' and more often than not this involves a lengthy reply which without a visual reference can be both difficult if not confusing. Well here's a link to an online lighting diagram which allows you (by drag and drop) to place various objects, backdrops, lighting and camera etc onto a canvas to illustrate what you may be attempting to describe. Once you've got everything in position you can then save out to PNG, JPEG or URL for adding to your post. Oh yes, it's free for non commercial use.
http://www.lightingdiagrams.com/Creator