This site is great for the student who wants to look up, read, or search any portion of Shakespeare's works. Not only are you able to read through the entire plays, but Open Source Shakespeare allows you to search the texts in a variety of ways (i.e. by character, word, line). You are also able to search cross texts, if you want to see the use of a word in multiple works. The text is based on The Works of William Shakespeare, ed. William George Clark and William Aldis Wright (Cambridge: Macmillan, 1866) -- the popular and influential "Globe Edition." Site is based at George Mason University. Handy mobile version at http://mobile.opensourceshakespeare.org/.
A pioneer site for digitizing literature (launched in 1993). This site is great if you are just looking to read Shakespeare online. The format is simple and accessible with links to the different plays and scenes in each play. Not good for citation, however, since there are no line numbers.
If you are looking for a specific edition of Shakespeare's works this site has a lot of them. While this site is an overload of links for everything Shakespeare, if you go to the "Works" page you will find links for most editions of Shakespeare's complete works including Samuel Johnson, Cambridge, and Globe editions.
The Rare Book Room has a compilation of Shakespeare's Quartos, First Folio, and a few first editions gathered from a few renowned libraries: including the British Library, the National Library of Scotland, and the Folger Shakespeare Library. These are all included under the section "The Quartos of William Shakespeare." This is a great site to see complete digital images of these original books.
A part of the British Library, this archive provides digital images of the early quarto editions of the plays. This site allows you to compare two texts at the same time online.
Available through the Hathi Trust Digital Library, the Samuel Johnson annotated edition of Shakespeare's works comes in ten volumes, including Johnson's influential commentary.
Want to see or hear some Shakespeare...
Shakespeare is meant to be performed. Here are some great links to visual and audio media of Shakespeare's works.
Student at the University of Minnesota...
Here are some links to other resources for Shakespeare's works only accessible to students and faculty at the University of Minnesota.