Along the lines of testing, you can do no better than Performable (http://performable.com http://performable.com) for A/B testing of landing pages. Also, read t

Along the lines of testing, you can do no better than Performable (http://performable.com http://performable.com) for A/B testing of landing pages. Also, read their blog. It answers OP's question, and so many more. As for collecting emails on a landing page, MailChimp (http://mailchimp.com http://mailchimp.com) is the best service I can think of for capturing emails in a CAN-SPAM-compliant fashion and look good while doing it. Campaign Monitor (http://campaignmonitor.com http://campaignmonitor.com) is pretty good, too.