Use pretty urls like /login instad of wp-login.php .With this plugin you can change the login or register url to whatever you want
This simple plugin use wordpress rewrite api to change login and register url to whatever you want. On activation by default will change wp-login.php to "/login" and wp-register.php to "/register". You can change these on the settings page.
Pretty Urls (http://www.masquewordpress.com)
Increase your Twitter followers with Social PopUP Plugin (http://wordpress.org/extend/plugins/social-popup/)