This Cassette Tape wall decal is huge at 2x3 feet. Retro and detailed, it even says "Mixed Tape" on the label. These wall decals are great because they don't damage the walls while they're up. They come off cleanly, with nothing left the behind. The only downside is once they're off of your wall, you can't use them again.
There is literally and endless supply of ridiculously awesome wall decals on Etsy, so I'll save the rest for other posts ;)