All About GEDCOM

Good introduction - illustrated!
(http://web.ukonline.co.uk/nigel.battysmith/gedinfo.html)

GEDCOM Explained - by Dick Eastman
(http://www.ancestry.com/learn/library/article.aspx?article=5743)

GEDCOM 101 - by Jan McClintock
(http://www.leisterpro.com/doc/olderversions/Articles/gedcom-101.php)

Good short articles on GEDCOM
(http://www.tedpack.org/gedcom.html)

Everything you need to know about the GEDCOM format
(http://www.robert-weinland.org/gedc.php?lang=en)

The definitive GEDCOM page
(http://homepages.rootsweb.com/%7epmcbride/gedcom/55gctoc.htm)

Institute of Genealogical Information Exchange
(http://www.igenie.org)

How To Create (Export) a GEDCOM File
(http://www.gencircles.com/globaltree/instructions)
Specific instructions for every Genealogy database program there is.