If you go to
http://www-106.ibm.com/developerworks/ and type LPI 101 in
the search field they have a pretty good intro to Linux there.
http://www.linux-tutorial.info/
Is a nice full tutorial
System Admins will proably like.
http://www.tldp.org/LDP/sag/c38.html
and don't forget my favority
http://rute.sourceforge.net
Also try
http://www.linuxtraining.co.uk/download/
for more advanced info.
I'm thinking of starting a newbie page if anyone has other links to add
I'll be happy to put them up.
Carl Parrish