Hard to beat Nik Silver Efects. You may have to click several of the links on Google to find the right one for the package, though, since the main link simply ends at DXO's site.
However, the Black and White Adjustment layer in Photoshop may also be a good place to start, but doesn't have the micro contrast tweaks you can get out of Silver Efects with much less effort. Blending layers also is another option, but after the B&W adjustment layers that came out with Photoshop CS3, I pretty much left that method behind.