Search engines
Introduction
use search technologies effectively, appreciate how results are selected and ranked
Self study resources
The research paper on Google's Bigtable
The research paper on the Google File System
Google's Search Education site has resources to help teachers and pupils develop better search skills. It includes A Google a Day - Daily challenges to develop search skills (click 'basic game' to start playing)
CS101 from Stanford - an introduction to computer science, how to build a search engine. Undergraduate level course, and one of the early MOOCs - later became part of Udacity.
Stephen Levy's In the Plex, is a well-researched comprehensive account of Google's work.
Resources for lectures or group study
I know off topic here but there's a lovely Page Rank simulation in Doug Aberdeen's presentation at the 2011 CAS Conference. You'll need to printout the relevant slides and have some dice available.
A good introduction to Google search.
Google's Peter Dickman on how Google Search works. (40' presentation at Google Big Tent event)
Resources for use with pupils
Beautiful collection of photos (and commentary) about Google's Data Centres.
Search Engine Tips.
Bing It On - Microsoft site to compare Google and Bing results side by side.
How search engines work - a case study including a collection of resources for teaching this topic at Key Stage 2 (see files at the foot of this page + http://youtu.be/u2WZAl0VXN0 ) by Pete Gaynord.
Modelling Google A class activity. [CC by-sa Graham Hastings]