Wikisocion or http://www.socionics.us/ are good starts. The first is community run, the second is run by an American who learned it while in Russia. Socionics.com has some funny stuff, but a lot of it is just the brainchild of the site runner (Sergei Ganin).
Socionics has always used LSI/SLI/SEI/etc.. It was never an offshoot of MBTI. It was developed almost in tandem, with no knowledge from Myers (and no knowledge of Augusta, on Myers' part). You can't really blame it for what it's not.
The Socionics.com writer (Sergei Ganin) was the first to start a website in the West, I think. He used the MBTI jargon for types as a way to help people who were already familiar with that system.