Designs that were uneconomic then are the cheapest way now.

As an example, I'd put forward a trick I was taught for doing fast lookups of phone numbers. Instead of doing a tree or other data structure that can be searched, implement your phone-number database as a 7-dimensional (for a single area code) array. Lookups are now constant-time, beating any other method. The only downside is that back in 1980 the 38 megabytes (assuming 32-bit pointers) to store the array would've been prohibitive. Today 38 megabytes would be somewhat hefty but well within feasible parameters for a decent server (I've handled in-memory data structures several times that size on small 32-bit machines). Cripes, my cel phone could probably handle doing it that way. A good example of an idea that isn't new, it's just that the tech's advanced to the point where that old idea's now readily feasible in practice.

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