Photoshop is an incredibly powerful program. I'm pretty sure that even if you worked with it on a full time basis you'd only scratch the surface of what it could do. I use very little of the tools potential, but I do have some favourite effects and I'm going to share one of them with you.
I wish I could take credit for it but the instructions came from a Tips and Tricks pdf that came with the program. It is for making woodcuts of your photos. It is not as effective with every photo but if you play around with some you'll soon find the style it works best with. Here it goes...
1) First of all make a duplicate of the photo you're going to use, a good practice to get into, it will save you grief. Chose Image > Duplicate Name it whatever you want and click okay.
2) Drag the background layer in the layers palette down to the duplicate layer icon to create a new layer. Double click on it and name it Woodcut layer.
3) Change the blend mode on the Woodcut layer from Normal to Multiply. Click on the Normal button at the top of the layers palette and choose Multiply from the menu that drops down.
4) Use the High Pass filter. Choose Filter > Other > High Pass. Set the radius to 1.6 and click OK.
5) Chose Image > Adjustments > Threshold and set the level to 127. Click OK
6) Blur the background. Select the background layer by clicking on its icon in the layer palette. Choose Filter > Blur > Gaussian Blur an set the radius to 6.3. Click Okay. If the image that you've started with is large you may need to increase this level to blur the background sufficiently.
7) You're done. Like the image? Choose File > Save As and save your work.
You can also save alot of time if you like this effect (or anything else you do over and over again in Photoshop) by automating the steps.