I found an interesting genealogy website: familytreeconnection.com - Like many sites, it's free to search, but to actually view any of the records requires a subscription -- and they only offer it at an annual price. Inexpensive for an annual price - $29.95.
However, while there are lots of great small databases, and some people might find several documents, a search on my surnames yielded one record, for my great grandfather, who appears in a 1928 list of masons. I knew he was a mason. He states this in a 1926 bio for the Who's Who in North St. Louis. I was a little curious what other information appeared on the record, but not $30 curious, though.
However, it did spur me to do something I had thought about before, but hadn't yet done. I went to the Missouri Grand Lodge website, and on their 'contact' page, there's a form, which contains 'I have a genealogy related question' as an option. I sent a request for any information they had on my great grandfather.
They sent me his 'initiation' date, the date he 'passed'. and the date he was 'raised.' I don't know what these terms really mean, but that's ok. So I now know he was a member from 1919-1956. They also told me he was never an officer, though if he had been, I suspect they would have told me the dates there too.
From a simple google search, I learned that Cardinals ballplayer Rogers Hornsby was also a member of the same lodge at the same time. (At least he was playing baseball in St. Louis from 1915-1926 and 1933-1937, so I assume his membership in the lodge overlapped my great-grandfather's.)
Update: This page has more information on what to expect to find from Masonic genealogical queries. Apparently individual local lodges may have slightly more information than the regional Grand Lodges, but still not a lot of biographical information is retained.
I sent my query to the grand lodge since their website contact page had a specific option for genealogical queries; that looked promising. And their response was fairly quick. (3 business days I believe.) But still, even if I were able to get a copy of my great-grandfather's petition to join, the only pertinent information it's likely to contain is birth date and address at the time of petition, and I know both pieces of information.