In the projects we have done we came across several extensions which our customers needed on top of Magento.
Use price of a simple product in stead of the configurable price
Aya Software has developed a solution for this: http://www.magentocommerce.com/magento-connect/simple-product-pricing.html
Delete submitted orders
Magento by default does not provide a function to delete orders. You can use this extension to upgrade the function for delete orders and to delete test orders.