Learning a language could be really fun if you could snap a photo of a word in your native language and find a translation quickly to another; for that I found **Google Goggles** http://goo.gl/rGuex; a convenient solution that also doubles as a QR-code reader (requires Internet access). Google Goggles only makes out the words in the image taken, and thus you would need to also install a translator **Google Translate** goo.gl/yOLpK to direct your image's text to for translation (I presume it isn't narrowed down to only Google Translate, of that however I am unsure). 

Also organizing to-do lists could be nicely done on tablets/phones. **Wunderlist** is my current choice to managing to-do lists, since it has both a chrome add-on ( goo.gl/nw6pI ) and a mobile app (here's the link to that on Android http://goo.gl/XkmK7). It helps you categorize your to-do's through separate lists, prioritize to-dos (only 2 priorities: either important by clicking on a star, or normal priority), and easily view/add tasks for nearing times, such as "Today", "Tomorrow" and "Next 7 days". You need internet connection for syncing.

Of the most obvious features for a tablet (or phone) is to have any needed reading material on the go, and easily accessible. If however you're reading from your computer, it could be more convenient to have a remote to help you navigate through your documents/presentation slides; reading easily without having to reach out for the keyboard. Although this might seem as lethargic behavior, it could be used to the contrary of purposes; for example using a treadmill while flicking through presentation slides or perhaps rehearsing a presentation (where there would be someone assisting with the slide navigation) without the need to reach out to the keyboard/mouse. Such apps would need wireless connection (WiFi and/or bluetooth; I think it varies- I haven't tried out remote apps much). The remote app I've recently came across is **Unified remote** goo.gl/lQfXi for which you should need to download a server on your computer (it also has a portable version). I haven't quite tried out this remote (or others), so cannot give a review.

Hope this helps. Happy learning!

(I apologize not all links are clickable, since novice users have a maximum of only 2 hyperlinks per answer in SO for preventing spam.)