http://en.wikipedia.org/wiki/Turing_machines, http://en.wikipedia.org/wiki/Quicksort, http://en.wikipedia.org/wiki/Dijkstra%27s_algorithm, http://en.wikipedia.org/wiki/Dynamic_programming, graph coloring algorithms, etc.

If we're talking computer science then I kind of have to agree that Unix and regular expressions are minor contributions if they even rank at all. There are several theoretical concepts and core algorithms which are much much more significant.

On the other hand if we're talking about computing and programming in general then they are pretty damn major, possibly on the top 10. One has to remember that CS isn't programming and programming isn't CS.