In 2007 with the release of the first iPhone, Apple provided television viewers with a really nifty demo of the new Mobile Safari browser. Their main point was that the iPhone does not require a special mobile page to still have a good browsing experience on such a small screen. Even without 3G or the ability to run third-party apps (features which have been added since), people went out by the millions to buy the phone.
But since then, many websites have created special pages for iPhones and other touch screen smart phones that have been released since, like Android and Windows Mobile 7. While these new phones work much better at viewing standard web pages than their predecessors, it is still much easier to view a page that is optimized for the limited screen real estate these phones provide. Nobody likes to zoom in and out repeatedly to click on things that are too small to tap with their fingers.
The great thing is that it's easier than ever to build a mobile version of a web page. If you're using a content management system (CMS) like Joomla, Drupal or WordPress, it's as simple as adding a plugin that redirects mobile site visitors to a mobile-optimized page. For WordPress, the plugin I most commonly use is WPTouch, which comes in both a free version and a paid version. There are other mobile plugins available for most content management systems, simply search your CMS system's website for the plugins to get started.
By default, most mobile redirection plugins create a dynamic page of the latest blog posts. If you're a blogger, the task is pretty much complete at this point, unless you need to insert mobile-optimized advertising. Consult the documentation of your mobile plugin or look over the configuration page for details on that.
But if your page is a static or semi-static page meant to find more customers for your business, there is more work to do. WPtouch's config page allows you to send all mobile visitors to a static WordPress page of your choosing. To begin, you need to create a simple page with no element wider than 200-240 pixels and tell the mobile plugin to send visitors to that page. What you do at this point greatly depends on what your site's goal is.
If your business has a brick-and-mortar location, sending visitors to your location is probably the first thing you'll want to do with the precious limited area you have to work with. Most mobile web users are exactly that: mobile. They're around town somewhere looking for somewhere else to go. If you put a small map and a link to Google Maps, it will enable their device to give them directions from where they are to where you are so you can make the sale.
If you operate a business with no fixed location and visit potential clients at their homes or businesses, providing a map will not do you much good. At this point, making contact with potential clients is probably your key goal. Start by putting your phone number very large at the top of the page and most smart phones will automatically make your phone number clickable for users to call you. Under that, a small contact form followed by some basic information about your business will suffice.
It's also good to make your mobile page look as attractive as possible. Gadget addicts (read: smart phone owners) love eye candy. If you're proficient at Photoshop or GIMP, create some shiny 3D buttons for the users to click on to visit other mobile-optimized pages for more information, and you'll see page views up for those pages.