It won't replace Photoshop anytime soon, but your Android device is capable of doing some basic photo editing that can make your shots look a lot better. From the photo gallery, just tap "Edit" in the dropdown menu. You can adjust a shot's exposure, add effects like "Fisheye" and "Film grain," crop, take out red-eye, and even adjust saturation and tint. Send the results to the social network of your choice, or choose to have them auto-uploaded to a photo service like Picasa – or to Dropbox, using the previous tip.
Ice Cream Sandwich offers another cool picture trick: taking a still frame from a video. While you're shooting, just tap the frame to take a snapshot. It'll be automatically added to your camera roll. If you don't have Ice Cream Sandwich, don't worry. The $2.99 Frame Grabber app will give you the same ability, albeit after the video is taken.