The Bible software that I use, Logos, is giving away a free copy of the Cornerstone Biblical Commentary on Matthew and Mark for free. Here’s the info from their blog:
We have arranged with Tyndale to give away the Matthew, Mark volume for free–no strings attached! For a limited time (until the Pre-Pub ships) you can head over to product page and add this wonderful title to your Libronix digital library absolutely free of charge. Use coupon code CORNERSTONE during checkout.