An index of common abbreviations used by OED Online is available at http://www.oed.com/public/abbreviations. This can be helpful when looking at words' origins and histories.
To save a citation for an OED Online entry, click the "Cite" link at the top of the entry to export it to several different citation management tools (including RefWorks) in MLA or Chicago format.
In addition to definitions, view pronunciation and etymology (click on image for larger view):
Perform an Advanced Search, with your search term in Quotation Text and Shakespeare as Quotation Author, to see a how particular word may have been used in Shakespeare's work (click on image for larger view):