I'm developing a WordPress plugin and I want to append some extra form fields in add new form of Users section inside admin panel without editing core files. Can somebody help me in achieving this.
You can use
this filter to add your fields. I don't know it's is a good idea or not but works for me :).
You will find a lot of tutorials for doing this, take a look here for example : http://justintadlock.com/archives/2009/09/10/adding-and-using-custom-user-profile-fields
You can use following hooks :
EDIT : But it will not add fields on the "New User" form since there is no hook for that : http://core.trac.wordpress.org/browser/branches/3.3/wp-admin/user-new.php
But you can :