Browser Testing

Litmus (http://www.litmusapp.com) allows you to test your websites or HTML email messages in practically every web browser and email client currently in use. You just put in a link to the site, or upload your HTML, and their engine renders the code in all the different programs and takes screenshots which you can easily flip through.

Unfortunately this service is not free, costing $50 a month, but it is well worth the price. Useful for web developers, indispensable for email marketers.