I don't know if a concerted "project" is the way to go. Yes, I think that if there was a "standard" that was loosely agreed upon, then peoples hardware that goes along with the software can be easily made and tested.

For my home development board, I have created a backplane with 5 ISA 31 way connectors (8 bit ISA slots), which has most of the pins for the 40 pin 8031/52 micro going to it. It has its one address decoder and latch. Each slot represents an 8K block in either ROM/RAM area (design aka me chooses). Onto this board, I have created a plug in 8K memory module and Adapter board to interface to an Ethernet card. I think modules are the way to go for the home experimenter. Sure, when a project is about to go into production, then create the all in one board with all the devices attached.

I like the idea of the tutorials section of the 8052.com board. If people when they experimented with a device, i.e RS485 got it going, write a tutorial for it, then it becomes availiable for people when they want it.