An administrator can either edit the beginning of the suggestion post and put a symbol or an "A" for approved or "D" for denied.
Or you can use ascii characters such as these: ☼♀♪♫◄‼☺☻3☺☻♥♦♣♠¶↨§↑↓→←∟↔▲çêëèîÿ£¥₧
But yea.......after deciding on which ones to keep, change the title.
Also, you can make the post a sticky and keep it posted at the top of the category.
Lastly, You can make a whole other thread that explains the ideas presented and you can put links to every single approved post.
This will cut down on a heap of approved posts in the categories.