Here's a free photoshop brush set that contains basic rendering brushes, as well as some custom sci-fi brushes I've made. Feel free to use them in any of your personal and professional work, and of course I highly encourage y'all to make your own, that's where the fun really starts;)

Made in Photoshop CS4, they'll work in previous versions and of course will work in CS5 & CS6 & CC+