I just re-found this link yesterday. InterVarsity Press has allowed BibleGateway.com to publish 16 volumes of their IVP New Testament Commentaries online for free. These are some of the better commentaries that you will find online for free. You can check them out HERE. If you are interested in learning more about InterVarsity and InterVarsityPress, you can check out their sites HERE and HERE, respectively.
Free Biblical Commentary