A FAQ of rejected ideas

If your company actually has an intranet, it's probably filled with lots of policy about this and that. It might even have a tool to search for departments or employees. But have you ever had an idea and presented it to your boss only to have them say, "oh, we already looked into that and decided it wasn't a good idea." What if the intranet included stuff like this? I call it "The FAQ of rejected ideas". It would document ideas previously discussed and ultimately denied. It would explain why the company chose not to proceed with such a brilliant idea. Wouldn't that save everybody time?