It was a tough week for dotcom nostalgia.

First Sun Microsystems -- the company that once claimed to have "put the dot in dot-com" -- got gobbled up by Oracle. 

Then Yahoo! announced that it will shut down GeoCities, the pioneering websites-for-everyone company.

Nearly a decade after the tech bubble burst, survivors are still staggering toward extinction.

Sun's technology isn't going away, of course. But the company that helped define an era will be no more.

GeoCities, bought for billions back when such deals were routine, was made obsolete long ago by the drop-dead-simple technology of blogs and social networks.

Still, the legacies of both companies lives on: a robust, many-to-many Internet has become an integral part of our economy and our culture. Functions once performed by proprietary machines have been commoditized, and a personal presence on the web is practically a birthright.

Unlike the more recent financial bubble, the dotcom bubble left behind something valuable and sustainable. 

Like the railroad bubble of the 19th Century, the dotcom era was built on a solid foundation of technology. Once the speculative mania passed, the underlying value of that technology remained.

The railroads proved their worth over decades. The net, still in its adolescence, will do the same -- even as some of its early stars fade away.