One easy way to switch up your routine and boost your spirit? Swapping out your desktop wallpaper every once in a while. With Spring in full swing, there's no better time to do so than now. We're not just talking generic stock photos you've seen time and time again, but übercool designs and illustrations that will get your co-workers asking, "Where did you get that?" Doubly awesome: the fact that they're all free. Ahead, check out our top picks that will have you dreaming of blossoms, bike rides, and sunny days.