Admin plug-ins

http://rudd-o.com/projects/wp-admin-themer/

http://codex.wordpress.org/Creating_Admin_Themes

http://wordpress.org/extend/plugins/adminimize/

http://wordpress.org/extend/plugins/easy-admin-color-schemes/

WordPress

http://www.binarymoon.co.uk/projects/bm-custom-login/
http://www.wprecipes.com/how-to-disable-the-please-update-now-message-in-wp-dashboard
http://codex.wordpress.org/Administration_Over_SSL
http://www.problogdesign.com/wordpress/custom-wordpress-login-screen/
http://wordpress.org/extend/plugins/bm-custom-login/
http://weblogtoolscollection.com/archives/2007/12/28/9-wordpress-admin-themes/
http://www.blogherald.com/2007/06/21/safely-modify-your-wordpress-admins-css-and-make-it-futureproof/