The current site (http://www.symbolicorder.com) makes use of pulp art, so perhaps something in that style. But, honestly, we're very open to anything that looks good. Surprise us.
Accepted File Formats:
We're pretty open so far as what we're looking for. The only strict requirements are that the logo work well in different color schemes as well as black and white and (maybe) line art so it can be printed on business cards, letterheads, etc. Additionally, it should look good both a small size (say on the back corner of a book) as well as larger (a t-shirt).
Lastly, while the logo is being designed for the name "Symbolic Order Publishing," it'd be great if it were structured such that I could easily open the source document and change that to "Symbolic Order Community" or "Symbolic Order Books" or whatever else strikes my fancy.