I think it is an absolutely marvelous idea, however, I am not sure I have the experience and knowledge to code it. I think however, a diagnostic module that:
1. Has one of each node type defined in core 2. Has a few comment 3. Has a forum (and its replies) 4. Shows taxonomy terms 5. Shows all blocks in Core 6. Has some aggregated feeds 7. Is extendible (so that you can add blocks/nodes/whatever emitted from other modules)
should suffice for this purpose.
Regards,
Kobus
[...] Something like the pot file generator that would pull all the themeable components into a single static html would be invaluable timesaver and make life a lot more easier for many themers. In addition, it would make the presentation of templates more clearer b/c people can see the themed site instead of a screenshot. Lastly, it make the themes more consistent b/c every core elements of core would be themed and we would won't end up with themes which choose to theme some modules and not others.