There are a lot of cribs out there these days that act as a full sleep system. They go from a crib to a toddler bed, and sometimes even to a base for a full twin later on. But not all of them do this, or live long enough to make it into all three incarnations.
I know both of my kids brother their cribs long before they could become even a toddler bed. Which should tell you something about my children.
For those leftover pieces, you might not know what to do with them. If the crib is intact you can always try and sell it, or maybe offer it in freecycle. But most are leery about taking a used crib, especially with all the recalls to hit the baby industry in recent years. You may not have as much success as you hope for.
Instead, why not get creative? Pinterest, home of all things DIY, has a ton of awesome ideas for upcycling cribs. Stylish, interesting and functional additions to your home are just a project away.
You could do a lot with this idea, because it is entirely based around your personal tastes for decor and art. I like the concept of converting the grip springs into a canvas board, because it is light weight and yet would easily hold different items. You could probably come up with some other ways based on this principle.