The Landmark Baptist Bible Institute online library has a lot of Baptist material available online. Some of it is by recent writers, and some of it is older hard-to-find material.
Abstract of Systematic Theology, by J. P. Boyce
A Manual of Faith and Practice, by William Styles
Bogomils of Bulgaria and Bosnia, by L. P. Brockett
History of the Welsh Tract Baptist Church, by D. V. Spangler
The Graves-Ditzler debate of 1876