All good suggestions.
Barnes' Notes on the Bible <-- already available with the 2.0 beta release
Treasury of Scriptural Knowledge <-- already available with the 2.0 beta release
Robertson's Word Pictures
King James Dictionary <-- already available with the 2.0 beta release
Nave's Topical Dictionary <-- already available with the 2.0 beta release
Webster's 1828 Dictionary
Strong's Hebrew and Greek Dictionaries <-- already available with the 2.0 beta release (in the KJV w/Strongs)