First things first: Aldiko is not the only app to offer free e-books to Android users. Amazon's Kindle app has been available for a while now, offering access to a wide range of free and paid literature. Overdrive serves up content through a partnership with many public libraries, allowing patrons to virtually borrow books. There are also a number of other e-book readers easily found by searching the Android Market. But many are restricted by proprietary delivery systems and digitally copyrighted content. Aldiko is a different breed.
Aldiko gives you access to thousands of openly-available books, ranging from timeless classics to self-published works. You can find these free gems from the built-in store. Also included in the store are current best-sellers, for a price, of course. These are the more typical DRM-protected books you're used to seeing from Amazon and others.
Arguably the best feature of Aldiko is the ability to import any electronic book from the SD card in your device. This means that you are not locked in to the offerings in the store, as is the case with most other reader apps, so you can gather EPUB- or PDF-formatted books from any source and read them on your Android-powered device. It's this spirit of open access that gives Aldiko the nod over its competitors.
Each week I recommend a useful, fun, or otherwise noteworthy app to explore. While I generally focuses on Android apps, many are also available for Apple products, and occassionally I'll throw a desktop application into the mix for good measure!
Know of a better e-book reader? Tell me about it! Add a comment below!