Has anyone ever installed rear leaf helpers? Are they effective?

I hat when i have stuff in the cargo area getting high beamed all the time. Saturday i had 6 people in the x one of which was in the rear area (better then a dui) but the whole ride home i kept getting beamed. This has happened during other trips when there are coolers or other heavy items back there.

So i was looking for a cost effective way of fixing that.

like these
http://cgi.ebay.com/ebaymotors/Heavy-Dut...040828033QQrdZ1

or

http://cgi.ebay.com/ebaymotors/3-Way-Adj...039391028QQrdZ1