CRE Loaded Google Checkout module advanced features:

• Support for Product Attributes
  Module supports product attributes with price modifications (like "Size XXL +$10")
• Support for Taxes
  All standard tax modules are supported "out of the box"! Unique feature: taxes are calculated on-line based on final billing address of your customer!
• Support for Custom Tax Modules
  Supports Tax Modules, created according to CRELoaded requirements
• Support for Shipping
  All standard shipping methods are supported "out of the box"! Unique feature: shipping costs are calculated on-line based on final shipping address of your customer!
• Support for Custom Shipping Methods
  Supports Shipping Methods, created according to CRELoaded requirements
• Extended Logging
  Very useful to see how your store visitors using this payment method
• Test mode support
  Enables you to test prior to enabling this payment method
• Ability to disable Google Checkout for specific products
  Allows to exclude products which are not accepted by Google
• Supports Google Analytics integration
  
  Google Analytics enables a merchant to understand how visitors interact with the merchant's website. Google Analytics also helps the merchant to identify navigational components that promote or inhibit conversions to sales, enabling the merchant to optimize ad campaigns and website content for increased sales.
  
  Google Checkout merchants can use Google Analytics to track buyers who leave their sites to complete the checkout process using Google Checkout.
  
  Google Checkout - Google Analytics official blog