Magento WatchDog
This smart adjustable extension will promptly alert you about malfunctions in your store and provide you with the information needed to fix those malfunctions faster (such as when, where and in what circumstances the errors occur). When something goes wrong, a lot of time might pass before you stumble upon the error, and even more time will pass while you try to find out the reason and fix it. Each store owner can estimate how much sales are lost during one hour of downtime, and sometimes the numbers are very impressive. With Magento WatchDog you will have more control over the situation and will be able to minimize the losses caused by system malfunctions and save on support services required to fix them. The extension is available for Community Edition and Enterprise Edition. Full list of features is available on the product page, see the link below.