Flowing Palette Demo is exactly what is says 🙂

Quote:

After days of non-stop work on this, I think it’s ready for some exposure (no source yet, as it’s still not cleaned up as much as I’d like). NTSC only:

http://blargg.parodius.com/nes-code/flowing_palette.zip

It works beautifully on my NTSC front-loader NES. I’m not sure it’ll work on emulators; if someone has a PowerPak and can verify that an emulator matches what you see on your NES, please post which emulator you used.

All graphics are generated by manually setting $2006 and $2007. After initialization, all code is cycle-timed, as this is the only way to get a stable image with this technique. I had been working so many days non-stop on this that I wanted to go ahead and release it, before I got the new PPU timing technique working that will eliminate the need for cycle timing everything, since that will require a big rewrite.

http://nesdev.parodius.com/bbs/viewtopic.php?t=6502