Many readily available saw blades now days are made using varying alloys with carbide tips. These likely won't work for knife making. Larger saw blades of known manufacturer can be had from sawmills, and depending on the blade and maker, can be suitable for making a knife. The biggest thing is to know what the blade is made from and how to appropriately heat treat the steel.
As for the maker's mark, there are two primary methods: stamping and etching. Stamping involves marking the blade using a stamp while the blade is hot and soft prior to heat treating. There are a number of manufacturers of custom stamps. Etching involves having a design made into a stencil by any number of stencil makers out there. Many here, including myself, use Ernie Grospitch. Any sharp and clean design that can be printed from your computer can be made into a stencil. Once you have your stencil, you use an etching machine (I made one from the Crawford Etcher designs available online) and a saline etching solution. Some people simply use a large lantern battery for etching with the saline. Typically, DC current is used to remove material, and AC etching is used to darken the etch.
--nathan
