Williams is still around in the form of Williams by Bachman but they are only 60 years old (and still kicking). They've kind of become the new "Marx" but with a much nicer/upscale product.
Williams did produce a great alternative line of trains that were well-made and economically priced. But now, other than the Eggliner (which is just a novelty item for under the tree), are they still making anything? Or are they just dumping NOS through TrainWorld, Mario's, et al?