You know, a wall with a whole bunch of different size frames and pictures that spans a large area and looks really cool.
Step 1: Get Your Frames
Buy a whole bunch of frames. Buy more than you need, you can always take some back. Buy a variety of frames, but mostly 4x6 and 5x7. Get a few 8x10s also. Try to stay away from more than two of the same frame in the same size, but whatever. It might also look good with all frames EXACTLY the same. I grabbed a couple composite frames as well- three or four photos matted and mounted in the same frame, but chose not to use them. It might work well in your setting, esp. if there is a common theme in a few pictures.
Step 2: Arrange Your Frames
I started out putting them on an old sheet (see picture), but quickly became smart. The key is laying them out on Christmas wrapping paper. Measure your wall and spread out enough paper on the floor to cover the wall area in question. This will be especially useful later. You'll see. Anyhow, lay the frames out and arrange them in portrait and landscape configuration however you'd like. I figured the upper and lower boundaries and line space between frames should be close throughout but not exact. You might like more precision. This step is key, because it is very difficult to change the frame order and placement after this. Also, if you've gotten all identical frames, you'll need to insure your lines are tight and even.
Step 3: Trace Your Frames and Mark Your Holes
Now that your frames are sitting on wrapping paper on your floor, you should trace around them (or at least the corners) to mark where each will go. A felt tip pen works well for this. Then remove the frame and number the newly empty paper square and the back of the frame. Mark where the nail hole(s) need to be for that frame. If you have any frames hung with a wire, just mark the frame location. You'll probably have to fine tune the exact placement later once the other frames are on the wall.
Step 4: Hang Your Template
Now you just stick the paper on the wall. (I'm reusing the same picture from the last step, sorry if the surprise has been ruined.) As you can see from the picture, I had some crinkling issues. You can just smooth the paper from the center as you go. This is where you should check for total composition level by measuring the distances from the floor/ceiling to your frame outlines on both ends of the paper. A bubble or laser level works too- whatever level of precision you want to bring to the party is great.
Step 5: Pound the Nails
Since you marked the template in step 3 with the nail hole locations, now you just need to drive them in the wall. Go for it. Then peel off the wrapping paper. Sorry for the low quality photo of this step, but you get the idea.
Step 6: Hang the Pictures
Now hang your frames. Look back at your template and the number on the frame for the placement. If you've already filled them with pictures, great. If not, I think it makes sense to "dry hang" the frames anyhow to make sure you're happy with how it looks. Realistically though, you should have made sure it looked good a few steps ago. Now just a few finishing touches...
Step 7: Finish It Up
Now you should have your pictures printed out (or enlarged) and arranged on the wall. Once they're in their frames, tear off the little angle brackets that allow the frame to stand free, and anything else that prevents the frame from sitting flush to the wall. If you have to tear off the latches that close the frame in, just put some masking tape on the back to hold it together. Next, get the frame on the nail, and push it tight to the wall and tilt it level. That should be it. Enjoy.