Yes, you can strip nickle and refinish to your taste, depending on what's under the nickle. Robar, Arizona Response Systems, Tripp Research can all do it.
There are two commercial formulas available to blacken and stain stainless steel. Brownell's Oxynate 84 and DuLite's 3-0 salts. They are both hot tank solutions and are more difficult to use than regular blueing salts. Neither of them is really a DIY process.