Here's what I have used so far.
Reading apps
Any apps that can't turn off page animation look pretty bad to me. These include Kindle, Scribd, and Google Play books. Some don't mind the distortion you see while the page is turning, but it's too much for me. Other than that they seem to work.
Moon+ is my favorite on my Nexus 7, and it works quite well here too. Just make sure you use the outdoor theme to get a white background and black text. Some if the menus have the white on white problem, but I used my Nexus as a guide for what settings I wanted.
Moon+ uses Color Dict dictionary and that works well. You need to install your preferred dictionary data, the ones you need are on the app install page. There are English and other languages available.
The Overdrive app works well, I downloaded a library book and turned off page animation.
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 and it's only when you go to the previous page.
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. There are even changes coming that help for eink.
I also installed InoReader rss reader and it works very well. IIRC it's a pain to set up so I restored the version that's on my Nexus 7 using Titanium Backup. Yes, Titanium Backup works if you're rooted, but the text is not visible in a number of places.
Other apps
ADW launcher - tried this one, but it seems to have caused "Unfortunately search has stopped" errors to pop up. It also did not return you to where you were in an app if you went back to the home screen - it took you to the initial screen in the app.
Nova launcher is what I am using now. Works great and you don't need to be rooted to use it. Using a launcher gives you access to the standard Android settings menu if you don't have it.
Home Switcher for Froyo - very helpful if you want to use a launcher app. It will list all launchers you have installed including the Onyx launcher. You can't see where you need to tap when it brings up the list, but just tap on the end of the line of the launcher you want. This allows you to have an Android launcher be the default when you tap the home button and still access the Onyx launcher.
Tapatalk installs and works too using the light theme, but quoted text can be hard to see.
ES File Explorer and Root Explorer are good file managers.
Swapps is good since there isn't a recent apps button. You can set favorite apps and widgets, recent apps, and all apps to come up with a swipe from within any app. The reader apps can't be in full screen so you need to tap in the center first.
Wifi widget - I use
https://play.google.com/store/apps/d...fitogglewidget . I have it in Swapps and the widget pops up in whatever app you are in and disappears when you tap another area of the screen.
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.
Amazon appstore, Dropbox, 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.
What apps are you using?