Atari 8 Bit Computer Projects

I put this here, in part because I like Atari 8 bit 6502 computers, but also because I really like how this idea of suggesting projects works:

You get a goal, estimated time, what you need, and each is bite sized, generally fun and many will teach the person who does them a little retro something.

Would be nice to see this spread. Obviously other 8 bit / old computers are easy targets, but so are things like the Raspberry Pi.