I thought it would be cool to build after I saw The King of Random's video on a recycled pallet wall.
Step 1: Cut, Wash and Brighten
Using a reciprocating saw and medium metal cutting blade cut the planks off. You can pry them off an remove the nails but I think the nail heads look good and the boards will split if you pry them off. Then you can use some wood brightener to brighten and clean the board off.
Step 2: Remove Trim & Paint
Preferably remove the trim before painting. It does not matter though. I painted it black because when there are gaps in the wood it looks good. You could paint it any color and it might turn out pretty cool.
Step 3: Mark the Studs
Find two studs and measure the distance in between them then use a tape measure and mark the distance in between studs along the whole wall.
Step 4: First Layer
Make sure the first layer is all the same width of boards. It will make it a lot easier as you go up. I just used some finish nails hold them up but if you have a brad nail gun it would go a lot quicker.
Step 5: Keep Stacking
Keep the boards roughly the same width on each layer.
Step 6: Finish the Top
When you get to the top you will need to rip the boards to get it to fit up against the ceiling. You could probably get away with out cutting any boards if you put up wide enough trim.
Step 7: Weathered Wood Accelerator
I used Varathane Weathered wood accelerator because I wanted to have a darker finish.
Step 8: Polyurethane
This step is unnecessary but I just wanted a finish on the wall so I can wipe dirt and dust off.
Step 9: Add Trim and Your Done!
I put some quarter round on the ceiling and a 1x4 on the floor if you had something thinner it would probably be better. And your recycled pallet wood wall is Done!