The on-line syllabus includes a number of additional links to resources relevant to the class. Here are a few more:
Classical Skepticism by Peter Suber.
More Advanced Articles:
In addition to the databases available via Dupre, my Epistemology Research Guide Subject Index has a section on skepticism has links to over 200 articles on skepticism in contemporary epistemology available for free online.
Finding Books on Skepticism at the Library:
Books on skepticism are all over the place in Library of Congress system. Books with 'skepticism' in the title and about contemporary skepticism tend to be in the BL837 section. Books on contemporary epistemology are in the BD143 - BD212 sections (with some other stuff mixed in), including books partially or totally devoted to skepticism. Books on Hellenistic skepticism and epistemology tend to be around B525. Books on Zeno's paradoxes tend to be at QC131. Books on vagueness paradoxes are at BC199.