Research & Documentation Online (Bedford/St. Martin's) provides information and examples for MLA, APA, Chicago, and CSE.
CheckCite (James Madison University) provides examples for APA, MLA, and Turabian (Chicago) for use in a paper, PowerPoint, or speech.
Quick©ite (University of Auckland, NZ) provides examples for APA, MLA, and Chicago.
University of Wisconsin-Madison Writing Center -- Writer's Handbook
American Antiquity/Latin American Antiquity (from the Society for American Archaeology)
Council of Science Editors (CSE) (from Ohio State University Libraries)