Who is the author/publisher? Are they a scholar/expert in the field?
What is the intentof the publication - to educate, inform, sell, persuade?
Is the information bias or objective in its presentation?
When was the source published or last updated? How important is currency of information regarding this topic?
Who is the intended audience of this work?
Is the research funded by an external body? If so, does that body appear to have a vested interest in the outcome of the research?
Tutorials
Choosing the Best Web Sources - An online tutorial that will help you recognize hidden web resources, determine if a site on the open web is reliable, and learn how to analyze resources on the open web.