While you are entirely welcome to share all ideas on this board, I have to warn you that I am only one man, and most of the suggestions probably won't get implemented.
To increase the odds of your idea making it into the game:
1. Make your idea clear, concise and accurate.
This includes reading over the docs thoroughly, and understanding the mechanics of the game in the area your suggestion intercedes.
2. Offer only well-balanced ideas.
This means balanced between government, resources, newbies and oldies, industry type, and whatever other elements of the game your idea touches on. I don't want any magic-bullets to world domination, but on the other hand an idea which adds a new element of feasible strategy is great.
3. Offer ideas which take minimal time to code.
The more complicated your idea, the less chance I'll have to do it as well as the many others people have suggested, as well as my own. If you suggest a new building, consider that as well as coding the building I have to go into POV-Ray and make a graphic for it at some stage. If you're suggesting a complex idea, it better be a doozy in terms of added fun.