i got a truck a bit over a year back. i keep a pretty good sized chain (pulled bushes out of the ground and moved a car with it) with an innertube over it in the back. i just have one end locked to a hook in the bed to keep someone from walking off from the chain it's self. it doubles as my bike lock when i transport one (some). i use it with a ratchet strap to keep the bike from moving around. won't help with parts of the bike that can be taken off (i tend to just have a bike back there when i'm directly going somewhere with it though), but not bad otherwise.
i might consider one of those new cargo vans like ford makes, but i have a motorcycle also so i want something sturdy enough to carry it when i want/need to. plus it's my first pickup truck. i kinda like having it more than i thought i would.