1. Put your camera on slow-shutter (night setting for some cameras) and get one person to take the photo, and the other person to duck right out of the photo right as they're taking it. If you do it at the right time, it'll make you look like a ghost! This takes quite a few times to master. Example: http://farm4.static.flickr.com/3159/2572005340_1028675c47_o.jpg
2. Find a spot with a beautiful sunset, and one of you take a photo of the other jumping in the air. On most digital cameras, you can half-hold down the button then when you fully press on it, the photo will take immediately. This helps when counting in for the jump, if you know what I mean. These sorts of photos work best if you jump off a trampoline, or jump on top of a dune or something so it's just the silhouette and the sky. Oh and make sure your flash is off! Example: http://www.natural-answer.co.uk/gfx/products_sunset_jump.jpg
3. Take three photos of you're friends face (pulling different facial expressions) then three of their body/arms (doing different actions like pointing, etc) then take three of their legs/feet (one with left one up, one neutral, and one with right up) then go on to Word (or something similar) and arrange all the photos so that the face ones are in a line, the body/arm ones are below them and then the leg/feet ones. Print screen this, put it on to paint, crop it, and you have a cool looking photo. This one's good because you can do it just at home. Example: http://i965.photobucket.com/albums/ae135/sheeba_queen/Profile%20Pictures/USE.jpg
4. Do you have an underwater camera? If you do you can take some great photos of you and your friend dressed up in fancy clothes and pretending to dance or something underwater. Increase the contrast on your computer to make the water look really cool. Here's a really cool example, but you needn't go to as much trouble as this.. even if it were taken in a pool it would be fine.. http://stylefrizz.com/img/behind-the-surface-underwater-photography-project.jpg
5. Get your friend to stand really far away from you, so they look really small in the camera. Then step in front of it and play around with how you can look like you're stepping on them, picking them up, etc, because you'll be closer to the camera... You're going to need someone else to take the photo for this. Hard to explain, but here's an example: http://www.kennelson.com/newblog/wp-content/uploads/2009/09/image47.png
6. Take a photo of you or your friend (close-ups turn out better in my opinion) with really cool make up on. Then, put this photo on to Word, and put a blank square over the top of it. Next, go onto google images or whatever and find a cool light, flash, or colour photo- save this to your desktop. Go back to your word document, and make the photo the background of the box. Before you click ok, move the transparency up to around 70% (you can play around with this amount later.) Now, you should see the picture of you or your friend, with a light but recognizable picture over the top. Once again, this is really hard to explain, but my dp is an example of one I've made.. Here's another one I've made... http://i965.photobucket.com/albums/ae135/sheeba_queen/Profile%20Pictures/Untitled2.jpg
7. Like the first answerer said, you can take some great photos using mirrors and reflection. Here's one you could try to mimic, that looks awesome in my opinion. http://www.photo-zen.com/slideshows/black-and-white-photography-01-03.html You're going to need to play around with the angle of the mirror and the camera, but in the end it's worth it if you get a photo like this.
Hope this helps!