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181 Google Tricks that will save you time in School - updated is an article that has, as it's title suggests, some great tricks for using different Google apps and resources in education.
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The tips include improving your search and finding what you need, using Google Scholar, iGoogle, Google Groups, Google+, Google Docs, Gmail, Google Calendar, Chrome and much more.
If you use Google's apps and resources, this is a must read.
Related:
Presentation on Google for Educators
Why I use Google's Products as an Educator (and how)