The fire bucket has become a favourite of ours - simple, cheap, efficient and a bit of fun to use and make. But if you can't get around to making one, I'll do it for you. See ebay for a bargain.
A VERY handy edition to our car-based camping setup is a small shelf or table on the rear door of our old Pajero. Of course it depends on what style of rear door you might have but for a side-opening door it works well. Check out the video. Very simple to make and cost nothing more than what I found in the shed and an hour of my time.
This short video shows how we make a 'Gypsy' swing from a couple of trees, a rope and a tarp. It's easy to set up and the kids (and adults) enjoy it at any campsite.