The following plugins are available for your use. All plugins are licensed under the GPL. If you have any comments / problems using them, then please do get in touch.
Add wp-ecommerce to XML sitemap
Add categories and products from your wp-e-commerce store to a Google XML sitemap.
NB: (Only required for WP e-Commerce 3.7 or lower). For 3.8 and up – I recommend Joost de Valk’s WordPress SEO plugin.
Download The Plugin | Find Out More
Ajax Subscription Forms for Campaign Monitor
This plugin will let you create a widget in any of your sidebars, add in your list ID, and account ID, choose whether to show the “Name” field as well as “Email”. You can also use it to create shortcodes to insert into posts/pages to show the forms inline with other content.
WP E-Commerce Dashboard
A selection of admin dashboard widgets showing key information about your WP e-Commerce store, including sales graphs, revenue graphs and other useful information.
Note: The free version of this plugin is only compatible up to WP e-Commerce 3.7.x. For a version that works with WP e-Commerce 3.8 see here » WP e-Commerce Dashboard
Split Test WordPress Themes
Serve different themes to your users, and use Google Analytics to measure the relative performance of each theme.
Track Twitter Traffic with Google Analytics & Twitter Tools
Add Google Analytics campaign tagging onto URLs posted to twitter by Twitter tools.