Schematics of circuits that don't include an 8052 but are often used in 8052 projects? Or include things like FGPA/CPLD which are completely apart from 8052 but, again, may be useful to those working on 8052 projects?

Absolutely right, There can't be any real world design comprising of 8052 alone since you can't use 8052 to interact with outside world devices in most of the cases. There are always drivers, glue logic, buffers, filters, signal conditioners, converters etc. in real world designs. So, in my opinion things totally apart from 8052 but useful with 8052 system should be allowed in hardware library. If you carefully look at the forum threads you will notice that more than 50% of the threads are not straight on 8052 but are regarding peripherals and their interfacing.

Regards,
Prahlad Purohit