Published by Sir William Ramsay in 1899. Emphasis on historical context and archaeological insights. [partial e-text; work in progress]
http://www.webminister.com/ramsay/rcg00c.shtml
Studies in Galatians by Pastor Darrel Cline containing detailed comments and personal application.
http://www.biblical-thinking.org/DOC-Gal/article.shtml
A verse by verse commentary written in 1535. Part of Project Wittenberg and in the public domain.
http://www.iclnet.org/pub/resources/text/wittenberg/luther/gal/web/gal-inx.html
Based on King James Version but interacts with other translations and occasionally delves into the Greek text. Don Krow is an instructor at Colorado Bible College.
http://www.behold.net/krowtracts/com.html