Computers have always been home to amazing artwork. The C64 has so many graphics modes that artists were spoiled for choice near the end of the machine’s life. Luckily, artists are still working on the machine and releasing stuff even now!
There’s also a comprehensive and detailed collection at CSDB of course but it does have a gallery. You’ll have to click through to each image to view it.
Here’s a wonderful ZX Spectrum gallery. The Speccy was known for attribute clash but despite this you can create really amazing work if you know what you’re doing. Check out this Binary Zone tribute to Speccy artist David Thorpe. You will recognise the loading screens!