Read on the run with eReader. The app is free; the books will cost you.

When boredom strikes, nothing beats a good book at your side. eReader makes it possible, turning any iPhone or iPod touch into the next best thing since the Amazon Kindle. Granted, it doesn’t endow your device with all the Kindle’s features, but it does make reading on the run as easy as swiping your finger.

The free app comes with a pair of public-domain books—The Last of the Mohicans and Tarzan of the Apes—to get you started, but you’ll want to browse the impressive selection of fiction and non-fiction titles at eReader.com. Most are discounted, and you can get an extra 10 percent off by subscribing to the free newsletter. Alas, the eReader app lacks a built-in bookstore like the one on the Kindle: It can download only those books purchased from the eReader site proper. (It can also download from Fictionwise, eReader’s parent company.)

Because neither eReader.com nor Fictionwise is optimized for the small screen, your best bet is to browse and buy on your Mac, then download your purchases via the eReader app—a quick and painless process. That said, we did manage to make a purchase using mobile Safari, so you can shop on the go if necessary. The average book consumes just half a megabyte, so even a 4GB iPhone or touch can store dozens of titles without making much of a dent in available storage.

The eReader app is a model of simplicity: Just tap a book to open it, then swipe your finger left to turn the page or right to go back a page—much like flipping the pages of a real book. Tapping the screen brings up a toolbar for viewing the table of contents, searching text, or adjusting the font and font size. Speaking of which, text looks razor-sharp no matter what settings you choose. eReader is fully tilt sensor-compatible, rendering pages in portrait or landscape mode depending on how you hold your device.

Though it may seem a bit awkward at first to read a book on a smallish electronic screen, most readers get acclimated quickly—then fall in love with the convenience of a pocket library. eReader may be little more than a rudimentary e-book viewer, at least in its initial release, but its value can’t be overstated. It’s a must-have app.