There are a number of great resources online for getting immediate access to early modern plays and their contexts. Some are more useful than others, and really, nothing can beat a hard copy of a critical edition of a play. But for cursory reading, I have a few go-to places :

• Renascence Editions: As an online repository of major works printed in English between 1477 and 1799, this is my first stop for a clean reading text of anything from Marlowe to Defoe.
• Queen’s Men Editions: Playtexts were a company’s primary asset, and as such, they were sold and revised and sold again. Thus, we see many companies performing versions of the same play at different points in time. The Queen’s Men bought and sold texts to their contemporaries, Admiral’s Men, most of which can be found here. And did I mention they are searchable?
• Open Source Shakespeare: A searchable, free, and user-friendly collection of all of Shakespeare’s plays and poems. While we aren’t officially reading any Shakespeare in the group this year, his company, the Chamberlain’s Men, were the Admiral’s primary competitors and some may find it useful to look at their repertories side-by-side.

These resources are all free to the public. But if you do have access through a library, Early English Books Online (EEBO) is really the one-stop shop for any early English playtext, including facsimiles and transcriptions. As a UIUC user, click here and then select the “go” button to search. I’ve found their Text-Creation Partnership (TCP) editions to be especially readable on an iPad.