This semester Redcliffe’s third years on the BA(hons) in Applied Theology can choose a module on 1 Corinthians. We’ll be getting really stuck in to the biblical text over the coming weeks and thinking hard about how the letter relates to our participation in God’s mission today.
Google books has a surprising number of good commentaries available to read. You can’t usually read the whole thing but with the size of some of the volumes, even a limited preview is well worthwhile!
Here are some links:
1-2 Corinthians by Craig Keener (NCBC series)
The First Epistle to the Corinthians by Gordon Fee (NICNT series)
The First Epistle to the Corinthians: a commentary on the Greek text by Anthony Thiselton (NIGNT series)
1 Corinthians: a shorter exegetical and pastoral commentary by Anthony Thiselton
First Corinthians by Richard Hays (Interpretation series)
1 Corinthians by James Dunn (T. & T. CLark Guides series)
1 Corinthians: interpreted by early Christian commentaries by Judith Kovacs
Paul for Everyone: 1 Corinthians by Tom Wright
Centre for the Study of Bible & Mission 
I hadn’t even thought of using Google Books like this before. Good call!!
This would be the best way to use Thiselton’s larger work anyway – that thing reads like an encyclopedia with all those long bibliographies (but they are useful).