Just like creating web sites, there are now fabulous hosted services that can help you get a landing page up and running in a matter of hours (complete with a custom URL). Two example services include unbounce.com and quickmvp.com. These are end-to-end solutions that lets you create landing pages using a drag and drop interface. The back end is fully instrumented and you can see all the analytics at a glance. You can either use your own email marketing platform such as Constant Contact or Mailchimp, or you can use the built in email marketing feature.
You can test a single landing page and look at how the funnel metrics change as you play with different distribution lists, product concepts and more, or you can do it all at once with an A-B test or a multivariate test (if you have a big enough email list to run it with.)
If you have the technical skills to build your own landing page from scratch, you can also use a more best-in-class service such as Optimizely which, like the above, makes it very easy to do A-B tests with landing pages.