Here is an app that lives up to its name. For starters, Cool Reader supports a wide range of ebook formats, including EPUB, FB2, TXT, RTF, and HTML.

In addition to that, the app can handle table of contents, bookmarks, text search, and hyphenation (it comes with hyphenation dictionaries for several languages). You can tweak virtually every aspect of Cool Reader: from page background and page margins to alternative fonts and external stylesheets.

Suitable for hackers and mere mortals alike, the Hacker's Keyboard supports a wide range of layouts, including English, German, French, and Russian

The keyboard replicates the regular keyboard layout, so it is perfectly suited for users who depend on the arrow, punctuation, Tab, Ctrl, and Esc keys in their daily computing. The Hacker's Keyboard works particularly well with the ConnectBot SSH client app.

BooksApp is a handy app for bookworms armed with Android devices. The app lets you keep tabs on your library with consummate ease. To add a book, scan its barcode, and BooksApp automatically pulls the book's data.

The added books can be organized into collections, and you can easily search the books by author, publisher, and subject. The app can also help you to keep track of books you lend to other people. When lending a book, press Lend Book and choose the lender's name from a list of contacts. At the end of the month, the app will remind you who has the book. Finally, you can export the books from BooksApp to a spreadsheet or upload the data to Google Docs.

A text editor that can handle large text files and a wide range of encodings.

More importantly, it features word count and search/replace tools which make it a perfect app for drafting articles. The only missing bit is a spell checker. Official website | Android Market | Further info

This is probably the most powerful app for tweaking CPU and system settings on rooted Android devices.

The app offers a mind-boggling array of options for your tweaking pleasure. Not in the mood for tweaking? CPU Tuner conveniently provides several ready-made profiles you can choose from. Official website | Android Market