GCF LearnFree
http://www.gcflearnfree.org/
GCF LearnFree offers a large selection of tutorials on tech skills, programs, and even school subjects like math and reading. Examples of tech tutorials include Microsoft Office, Gmail, Google Docs, Facebook, and more!
Microsoft Office Training
Office Training Center
The Office Training Center offers tutorials and guides for using Microsoft Office apps like Word, PowerPoint and Excel.
YouTube
youtube.com
Not just for viral videos! YouTube includes tons of training videos on using technology, software, and the web. A simple search for "how to use Prezi" retrieved thousands of videos!