The /etc/skel dir is mainly there for the adduser program to provide you with a default template for creating new users so you don't HAVE to do it manually. This will provide them (new users) with all the default X settings, shell settings, desktop settings, icons, etc...(skel is short for skeleton)--you can also create modifications based on this dir.
ex. in my office we have a dir called "/etc/skel.csr" and a modified "assuser" script called "addcsr" this way all we have to do to add another user in the "csr" group, we just type "addcsr <username>" and it creates an account/homedir for the user that is identical to all the other "csr" accounts-can save a lot of time for administration.
Hope It Helps!