Talonite - Stellite 6K - Boye Dendritic Cobalt(BDC)
These cobalt alloys have incredible wear resistance, and are practically corrosion resistant. Stellite 6K has been around for years, but was expensive and very difficult to work, and so is only rarely seen. Talonite is easier to work, and as a result has been gaining in popularity, especially among web-based knife buyers. David Boye uses his casting process to manufacture Boye Dendritic Cobalt. This material is tough and has great wear resistance, but is relatively weak.
Newer titanium alloys can be hardened near 50 Rc, and at that hardness seem to take something approaching a useful edge. It is extremely rust-resistant, and is non-magnetic. Popular as expensive dive knives these days, because the SEALs use it as their knife when working around magnetic-detonated mines. Mission knives uses titanium. Tygrys makes a knife with a steel edge sandwiched by titanium.
Numerous knives have been offered with ceramic blades. Usually, those blades are very very brittle, and cannot be sharpened by the user; however, they hold an edge well. Boker and Kyocera make knives from this type of ceramic. Kevin McClungcame out with a ceramic composite knife blade that much tougher than the previous ceramics, tough enough to actually be useful as a knife blade for most jobs. It is also user-sharpenable, and holds an edge incredibly well.