A lot of the Google technology is based on statistical analysis, which only really works well for huge data sets. Accordingly, a lot of Google's services exist

A lot of the Google technology is based on statistical analysis, which only really works well for huge data sets. Accordingly, a lot of Google's services exist so that Google can build giant data sets based on your use. As far as I know, Google records (or can reconstruct) every single byte that you send/receive through its services except for a few of your IP address, in order to build these data sets. For example, Google Reader is free so that Google can collect attention data. Google Analytics is free for the same reason. Google's 411 service is designed to collect voice data to fine-tune its voice-to-text engine. Some of those services also provide a platform for presenting the user with tiny classified ads, which is an additional revenue stream for them. Finally, some services are offered for free with no SLA and no customer support in order to stress-test the paid versions of those same products (Google Apps, Gmail).