The very talented Phil Coffman, founder of the equally impressive Method & Craft put up a very useful tutorial video on "pixel-hinting," which basically boils down to making small adjustments in Photoshop to ensure that vector-based imagery (logomarks, icons, etc) fall directly on the pixel borders. While perhaps a minor detail, it can add up to a large visual difference in crispness and overall quality and is essential for anyone that is creating top-shelf design work, whether for the web or mobile apps.
http://methodandcraft.com/videos/pixel-hinting-vectors-in-photoshop
