s2Member® Pro Login Widget

Integrated specifically to meet the needs of s2Member installations; s2Member Pro's Login Widget is specifically designed to work with s2Member (this comes with any purchase of s2Member Pro). It can also be integrated via PHP; i.e., you can even embed it into a theme file or another plugin if you like. See also: s2Member Pro Login Widget

Sidebar Login (Free Alternative)

Sidebar Login is a free alternative to the s2Member Pro Login Widget. See: http://wordpress.org/extend/plugins/sidebar-login/