Back in the day I believe the only other info out there was from the Tanners. They opened up the can of worms, so to speak!
The Tanners were the first modern ministry to the LDS (there is an online collection of nineteenth century ‘anti’ material that is a facinating read).
Then there was Ed Decker and Bill McKeever, the Higleys, and a few others.
Now, is is all over the ‘net.
When i left, the internet was still young (early early 1990’s) so I still had to do my research the old fashioned way, looking up sources by hand, tracking down books, cross referencing. It took almost a year of full time study before I found everything that can now be found in a few hours online.
The internet is doing a lot to get the truth of Mormonism out there, to stop people from joining, and to get people out.
Most major ministries to the LDS have an online component, and that is a good thing.