PlayShakespeare.com's Shakespeare App is a great addition to your device if you're studying the plays, or are an English teacher. It comes in a free version, but it's well worth spending a modest €2.39 on the Pro version for some very useful features. The app includes the entire corpus with a variety of useful tools. Pupils/students usually study a single play, but the purchase is still definitely justified: the Pro version includes line numbers, bookmarks to return to key quotations, and, impressively the most powerful new feature of Shakespeare Pro is a searchable glossary based on the bestselling lexicon by David & Ben Crystal, Shakespeare's Words. You can also activate the inline glossary to see all the glossary entries while reading the text. Simply tap on a word to see its meaning.
The search function (like our favourite Shakespeare Clusty site) is also very useful; if you're studying Macbeth, look up all the instances of 'blood' or 'sleep'. There are also features on portraits, facts, and scansion (nice but nothing you can't find quickly on the web).
Leaving Certificate candidates preparing for King Lear this June would certainly find it handy. You need to keep looking at the play, keeping it fresh, checking on individual lines and characters. So here's a way of using that downtime in the shop queue, the dentist's waiting room, waiting for that favourite soap opera to start...
Buy it here on the iTunes store; the free version is here (lacking some key features, but still has the entire text).