I'd say that most people posting here are American style leftist. They like the idea of single payer heath care and social programs to help improve the general welfare. Somewhat left of President Obama and right of Dennis Kucinich. With out knowing how much you know about American politics I don't know if that means much to you.
There are a few posters who are on the right American politics-wise. These few would have been considered somewhat extreme right a few decades ago, but they are pretty moderate for the current American political situation.
I'd say that there are none to no communist, but probably some people who would identify themselves as socialist.
How up on Neo-Marxism are you? I had some exposure to some decent Neo-Marxist works in college but it was all oriented to very specific issues without much general theory. I have always been a little curious to read some of the better minds on that side of the spectrum so if you could recommend some authors or works I'd check it out if I ever free up my reading backlog.