Consider the New York Post, which launched an iPad edition in October.

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Newsweek sells 12- and 24-week subscriptions to the iPad edition, though Apple handles the transaction and Newsweek doesn't know who the subscribers are.

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Forbes itself has been late to market with an edition for iPad, which just launched last week.

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Another app, called AmpliTube Slash Edition, allows users to turn their iPhone or iPad into an amp.

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The New York Post is the latest newspaper to cross the iPad barrier, with a new, full-content tablet edition readers will be able to purchase as a monthly or annual subscription.

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Last year's digital edition of TS Eliot's The Waste Land for the iPad proved that literature-related apps could be profitable when it earned back its costs in six weeks.

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Customers can also preview the app in real-time on their iPad, a time-saving feature to ensurean accurate look and feel, and update their Single Edition apps at no additional cost after they have been submitted to (and approved by) the Apple App store.

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