I'm not sure what he does now other than rake in that sweet 10bux, but he used to be a video game reviewer, comedy writer, and MLM Mangosteen juice salesman who worked hard for the good things in life like a $1000 “Aeron” office chair. Like so many people on the Internet, he started out funny then sort of washed into the background of the many troubles of running a really big web community. The target of many personal attacks (see previous three sentences), he eventually sort of lost it and his rule over SA became a mishmash of unenforced and over-enforced rules.
That's really all you need to know about him in the context of this site, but if you'd like to learn more, ED is always good.
See also this for his mention on the “lamest edit wars on wikipedia” page.
If you don't know this already, it's an interesting side note: Lowtax took his nickname from Byron Low Tax Looper, the one-time tax assessor of Putnam County, Tennessee. Looper took everything too far including legally changing his middle name to “Low Tax” as a campaign gimmick, abusing the powers of his office to harass personal enemies (real and perceived), and finally by murdering the man running against him for State Senate in 1998. The original Lowtax is presently serving a life sentence for his many crimes1).