We recently launched a new website, http://testingbot.com where you can do cross browser testing of your websites/webapps. We run tests of your website on different browsers, that way you know that your website works properly in all the different browsers. There's also an option where we can run tests for you on a specific time and interval, when a test fails we can alert you that something on your website is broken. Please let me know what you think.
Our service is web-based and we use Selenium, which is the industry standard for testing websites in multiple browsers. By using Selenium our customers can write very specific tests, for example verifying if a sign up form is working, or checking if a specific div is in the DOM. With our TestLab feature we can run tests you've created on a daily/hourly basis and alert you when something is wrong. This way you don't end up loosing customers and revenue.
Yes it works perfectly for ecommerce websites. With our service you can test if your cart process is still functioning, test various parts of your website, ... We're also giving out Seals which you can put on your website to indicate that your website is being tested daily on all browsers. If you're interested in a free test run, please PM me.