Looks like a great plugin but uses several deprecated functions:
line 25 load_plugin_textdomain
line 247 register_sidebar_widget
line 251 register_widget_control
Also if you simply go through and update the function names, you get the error:
wp_register_sidebar_widget missing argument 3
It's possible to correct these issues oneself, but the plugin in its present state (version 1.0) is not compatible with WP 3.7.1 out of the box.