This article is from the X-Men Comic Books FAQ, by Kate the Short (firstname.lastname@example.org) with numerous contributions by others.
Kid Dynamo is a fan-fiction written by once-netter Connie Hirsch, which
deals with the New Mutants in the days just after Magneto took over the
School (right after New Mutants #52). A very good story by any
standards, most people who have read it have granted it automatic status
in official Marvel history, vastly preferring it to the eventual rise of
Cable and the appearance of X-Force, or at least delaying that
inevitable occurence by including Kid Dynamo.
You can find Kid Dynamo on the Fonts of Wisdom Bootleg page. The URL is
http://home.att.net/~lubakmetyk/bootleg.htm . The fanfic is very long,
by the way; 12 full-size chapters. It takes a while to read. It's worth
it. (You can also find it on the http://www.csua.berkeley.edu/~tsang/kd/
or http://ebonbird.tripod.com/kiddynamo.htm sites.)