There are as many types and brands of tampers as there are pipes and pipe makers, both past and present.
I've found that the cheap aluminum nails with the tamp on one end and the spoon on the other work great for me. I prefer cheap, because I'm always misplacing them. I actually purchased a big bag with a mix of both these and the type that Al posted above.
I've used everything to tamp with, Nails, Screws, sticks, my finger and even a rock I picked up when on the river and forgot my tamper.
That being said, I've made quite a few tampers and sold some as well as gifted quite a few. Handmade tampers can be much like pipes and even lighters. It's all in the eyes of the beholder. I've made them in every shape and form and from a long list of materials, sometimes mixing several materials all in one tamper.
Different makers use different materials for the tamp end as well, some going with flat ends, angled ends and some even dishing the tamp end. I've used stainless, aluminum, steel and even copper on a few.
What all this boils down too:
1) Find the tamper that appeals to you. Some can even compliment the pipe your smoking.
2) Find a tamper that works for you and your smoking/tamping situation.
3) Try making one of your own that fits you. It can be fun, easy to do and give you the pride of having a smoking instrument that you made yourself.
4) Anything can be used to tamp and get the job done in a pinch.