Here's some of what I've installed so far. There's also a post on The Digital Reader for apps -
http://the-digital-reader.com/2014/0...comment-536923
The Overdrive app works well, I downloaded a library book and turned off page animation. Google Play books installs, but you can't turn off page animation so it looks pretty bad. Mantano works ok, it seems to have a page animation if you tap on the left of the screen but looks way better than Kindle, Scribd or Google. Moon+ works the best so far.
Calibre Companion works very well, I have 800+ books on my T68 now. If you use Calibre, Calibre Companion is a must have for organizing your books on your device.
I also installed InoReader and it works very well. Tapatalk installs and works too. I had trouble with Opera mini - I couldn't make the fonts big enough and it crashed too. You can't install Dolphin mini through the Play Store, but I installed it on my Nexus 7 and restored it using Titanium Backup to the T68 and it's working better than Opera Mini. Yes, Titanium Backup works if you're rooted, but the text is not visible in a number of places.
Amazon appstore, Dropbox, Swapps, Gsam battery monitor, and Thumb Keyboard all work. I am running out of space to install more apps! I have moved everything that allows it to the sd card.
The one issue in multiple apps is a problem where text doesn't show up on some menus - a sort of white text on white background, but usually in areas you won't need often.