I use Mantis Bible. They have an expanding body of resources available which include various Bible versions. (I have KJV, ESB, and Geneva) There are various commentaries (including Calvin's Commentaries) and books available. The items you want are loaded into your device so access is not limited to having internet access. A real plus for the iPod Touch.

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Soli Deo Gloria

John Schultz
Member, Riveroaks Reformed Presbyterian Church (PCA)
Germantown, TN

"The reason why we worship God in a slight way is because we do not see God in His glory"
Jeremiah Burroughs