These are the links that were used for demonstration at the 12 April 2012 FTM & CG SIG meeting.  If you are new to DNA for genealogy, I recommend checking out the last three links first then the FAQ and Glossary links for more details. The last link is to a video with Spencer Wells who explains how DNA testing  has evolved and is being used for genealogical purposes is probably the best place to start for background if you have 20 minutes to devote to it.  Note that some of these links require a login or ID to access fully.  

Family Tree DNA: http://www.familytreedna.com/

MyFTDNA Home page: https://my.familytreedna.com/default.aspx?

FAQ's: https://www.familytreedna.com/faq/answers.aspx?id=17#626

Glossary: http://www.familytreedna.com/faq/answers.aspx?id=21#781

Interpreting Results: http://www.familytreedna.com/pdf-docs/Interpreting-Genetic-Genealogy-

Results_web_optimized.pdf

Ancestry.com

DNA Home page:

http://dna.ancestry.com/viewConsole.aspx;jsessionid=DF804F8021DB85F35AD83F10142CFE02.dna03

Matches: http://dna.ancestry.com/compareY.aspx?uid=2607344&tid=129549

FAQ's: http://dna.ancestry.com/faq.aspx#testingRightForMe

23andMe: https://www.23andme.com/

ySearch: http://www.ysearch.org/

MitoSearch: http://www.mitosearch.org/

Gedmatch: http://gedmatch.com/

Other DNA Resources

Use of DNA Results Explanation: http://blairdna.com/dna101.html

Kerchner's DNA Testing & Genetic Genealogy Info and Resources Page: http://www.kerchner.com/dnainformation.htm

Spencer Wells builds a family tree for humanity:

http://www.ted.com/talks/lang/en/spencer_wells_is_building_a_family_tree_for_all_humanity.html