I use every single one of these several times a week.
From left to right:
Big, black one is a rubber mallet that you can get at the hardware store. One end has hot glue gun dots on there for texture when I pound metal sheet. Way cool texture. The other end is smooth. It is great for bottle caps and pounding things that you don't want to get marks into. If your piece is larger than the hammer head, then a metal hammer head can mark it up.
The rawhide mallet is next to it. I got that off eBay. I use that all the time for shaping because it also will not mark up your metal.
The silver double headed one is a tack iron and I got that at the hardware store. I use it for pounding in nails and for pounding wire flat.
The one that is second from the right is a riveting hammer. See the sharp end? That is the end I use for making rivets. The other side is slightly rounded so that your end will spread out in a flowering shape and finish the rivet. It is important that you get a riveting hammr with a smaller, thinner sharp end for smaller rivets. If you get a riveting hammer with the sharp end too thick, then it is not as easy to split the ends of your wire to start the rivet.
Email me if you want to know how to make a rivet from a piece of wire. I will eventually do a youtube video on how to do it.
The last hammer is a ball peen hammer. It is also called a chasing hammer. It has a slightly rounded end for rivets. I use the rounded end if I want to split the rivet more - if my hole is slightly too large. I use the other end for pounding stuff out on the bench block. The round end is also good for when I want to make metal disks on the dapping block. Mine is from Volcano Arts. I really like the feel of the handle and it has a good weight to it for an easy swing.
Sometimes, it is better to get the smaller hammers if you will be working on smaller pieces of jewelry. It is also easier to handle. Sometimes cheaper is not better with hammers. You need to check to make sure the head is securely on the handle. Sometimes, the cheaper ones are not one very well and will come off or wobble. That can ruin your piece.