As with most things in Photoshop, there are several ways to sharpen an image. One of my favorite ways is by using the High Pass filter:
1. Duplicate the layer you want to sharpen.
2. Go to Filter>Other>High Pass
3. Enter a radius of 1-10, click OK
4. On your layers palette, set the blending mode to Hard Light
5. Drop the layer opacity until you find the strength you like
I like this method because I can control it more. Also, it's not destructive since you can easily delete the duplicate layer you made. Hope this is useful for you!
Use the Eye Dropper tool to sample any color on your screen by clicking and dragging from your document to anywhere on your screen, even outside of Photoshop.
“Imagination is more important than knowledge. For knowledge is limited to all we now know and understand, while imagination embraces the entire world, and all there ever will be to know and understand.” - Albert Einstein
*UPDATE* - I hear you guys! I wish Adobe included this feature in every program they make, but unfortunately, they don't; however, they DO include it in After Effects, Lightroom, Premiere Pro and Soundbooth (all CS3 versions). So, if you use any of these programs, make sure you take advantage of this great feature.
Before everyone gets their hair up, you should note that they did NOT announce that they're changing the Photoshop icon, they're simply tying all their Photoshop products together for marketing purposes.
If you don't have a tripod and you're shooting hend-held in low light conditions you will probably end up with blurred images. Usually these images are blurred towards a specific direction. Because of the tiny shakes of your hand, you are basically applying a motion blur to your images.
You can help the situation with Photoshop's built-in Smart Sharpen filter. Just select the motion blur option in the drop down menu within the filter window.