I have an iPad, so my suggestions are pretty iOS specific and may not all be available for Nook, but hope it gives you an idea of potential:

1. Reading pdf facsimile eBooks from Gutenberg and elsewhere (though they require quite a bit of guts to render - my iPad 2 struggled, but my iPad Air manages much better) - I much more enjoy the original scanned pages than text-based versions

2. Paper by 53 - a simply wonderful drawing app that lets even people with zero talent or training (me!) create something actually usable. I wrote and illustrated a children's book, and also made graphics for a work presentation using it. I'm sure there is something similar for Android apps

3. Reading news - for this my favourite app is now Zite but others such as Flipboard are also good

4. Writing - I have a Logitech keyboard case, and it's a very portable, very focused experience, as you can't so easily "move to another window" as you can writing on a laptop

5. Video editing - I recently discovered that iMovie can edit native files from my videocamera, so I'll be doing more of that for work and play

6. Watching video - I subscribe the the BBC's iPlayer app which has a vast amount of content, plus I watch YouTube on it

7. Games - interestingly, despite being a major iOS gamer on my iPhone (I even have this website - http://www.rpg-site.com) I barely play on my iPad. But certain games like card games/patience are perfect on it

8. Recipes - I use the http://www.pepperplate.com apps on both my iPhone (where the shopping list is great) on the iPad (where it's great as a cookbook in the kitchen) and on laptop, where it's great for aggregating recipes