ScrubIT (filters pr0n, so probably not what you want): "ScrubIT offers clean, reliable, and speedy DNS service FREE of charge. Our filtered DNS scrubs out the bad stuff and is absolutely simple to setup and use. Try it today!"
* 188.8.131.52 * 184.108.40.206
OpenDNS (you'll get ads on DNS misses): "Taking a few minutes to unbundle your DNS service from your ISP's Internet connection means a safer, faster, smarter and more reliable Internet experience for everyone in your household."
* 220.127.116.11 * 18.104.22.168
vnsc-pri.sys.gtei.net (no idea who or what this is; but their DNS sure is open):
If your primary use is reading e-books, don't even consider anything with an LCD screen. These devices are typically called tablets. Look at devices with e-ink screens, which are typically called e-readers.