In 2010 a person calling himself SYD designed a fully functional clone of ZX-Spectrum 48/128 using modern electronic components that are currently available on the market. His Speccy was built upon FPGA Cyclone II, ARM processor and SDRAM making it relatively simple to replicate and at the same time very attractive as a great platform for experiments with those components. Not to mention that the source code is open and freely available for download and subsequent modification. Taking into account that the hardware part incorporates 8-bit color VGA, Composite and S-Video outputs for physical connection to either TV or monitor, 8-bit stereo output, SD card slot, two PS/2 ports for keyboard and mouse and two joystick ports - all this makes the platform a great starting point on the way to design your own game console.
We decided to buy a bare PCB and bunch of components and assemble it by ourselves. That is what we've got as a result.
All documentation is available at Google Project Hosting http://code.google.com/p/speccy2010. Unfortunately, it is in Russian only.
A 'Complete Guide For Non-Russian-Speakers' is available here: http://matt.west.co.tt/spectrum/speccy2010/