I have been a long time user of e-Sword (alongside BibleWorks and now also Logos, for which there is also a free version available) and cannot recommend it highly enough. It is a free Bible study software program that rivals many that you would have to pay for and is better than most. This program also makes basic word studies a breeze and has been of great use to those in my congregation to whom I have recommended it. In fact, they often tell me that they love the layout and how user-friendly the program is. There is not a very steep learning curve with this program, so most anyone can catch on to it fairly quickly.
Well, now e-Sword Android is available for Android, although this version is not free. It costs just $1.99 at the Google Play Store.