Here are the Portal 2 loading screens (animated) that feature the chronology of Aperture's logos. The above image only shows the 5 logos. Grab the actual individual animations from the download link at right.
Long version (for raster integrity purists):
These come from the VTF textures for 4:3 and 16:9 screens, ripped directly from Portal 2's GCF files, stretched to the appropriate aspect ratio (since the originals are all horizontally distorted to fit into a GPU-friendly 1024x1024 square), and left otherwise unaltered. Strictly speaking, this isn't the 100% bona fide Valve original, as there *was* a numeric loss of gamut in the conversion to a 256-color animated GIF. However, speaking as a professional in the digital image industry, I couldn't see any appreciable change in overall image quality, and I'm VERY picky. Yes! My standards are good enough for you! You will be satisfied and want nothing higher res! Yes!
Obviously, I take no credit whatsoever for the creative content of these images. I just did a little technical drudgery to make them more accessible. So this isn't really "fan art." Regardless, I just wanted some high-quality Aperture wallpaper after Portal 2 left me feeling totally jazzed enough to provide what Google images could not. And if for some reason Valve feels I've infringed on their rights by posting this, I only ask that when they ask me to take it down they do so gently. I scare easily.