[nl]

But Google is (historically) a software company, so we should compare its contributions in the software field at the moment.

Here's a random list:

Page Rank

Map/Reduce

Statistical Language Translation

Unsupervised image feature extraction[1]

Go

Dart

Large scale software defined networking.

The list could go on..

[1] http://arxiv.org/abs/1112.6209

[iribe]

dremel(where facebook's presto comes from) bigtable(where amazon's dyanamoDB comes from)

Most tech companies have google to thank for large scale data processing. Google could have not published anything, but they chose to publish these papers. There are other papers published that other companies haven't even started copying yet, as google is 5 years ahead of the industry in terms of large scale data processing. When these companies get there, they can check out the published papers, saving years of time.