- Mostly recommend a good PDF reader. Fast is good, but color accuracy is important. Apple has some sort of internal rendering engine that is quick but saturates and darkens color imagery. Unfortunately a lot of readers use that engine to display PDFs themselves. I prefer GoodReader (full version) for being a full-featured app, including connectivity to multiple cloud services. The rendering is accurate and the speed reasonable. It also does a nice job caching pages so you can thumb through them finding your place in a book or document.
- Also recommend Office unless you're married to Google Docs. The suite has gotten much better in recent years. OneNote is especially nice if you're not committed to Evernote. I keep an Office 365 subscription and so have full access to the suite, but I understand that non subscribers can get reasonable basic access to editing stuff.
- A good password manager if I'm allowed to nag about good security practices. I use KeePass mobile, but I know others swear by OnePass.
- A decent dice roller. There's some colorful ones you can shake your tablet to, but I won't make any specific recommendations.
- Anything else you use on your other mobile devices, if any, (social media, RSS readers, etc) and anything that connects to your professional life (I keep an algebra engine, Wolfram Alpha, a basic circuit simulator, and a paid calculator on mine).
I don't have anything BT specific and don't recall if anyone has developed anything that is intended for the tabletop. Record sheet apps for instance. I haven't seen any.
Regarding games:
It depends on what you want to get out of the tablet and what games, if any, you like. I could recommend anything from good free-to-play games to full-scale premium RPGs such as Knights of the Old Republic or the Baldur's Gate series.