Congrats on your new device!
My MUST haves:
A calculator app
A camera app (I recommend Camera Launcher for Nexus by Modaco)
A kitchen timer (I don't use mine for anything kitchen-related, but it's a good productivity app if you're prone to procrastination)
Dropbox for cloud storage
Google Drive (I gave up on MS Word ages ago and exclusively use Drive's word processor)
Evernote for cloud storage, note storage, bookmarking, etc.
GrooveIP for making phone calls (You can also try Talkatone, but I removed it earlier this week after not being able to answer incoming calls on my Google Voice number)
Google Voice for sending sms messages (who wants to be tethered to a mobile phone for texting? lol)
ColorNote for note taking/storage
Google Keep for note taking in a hurry (Brand new from Google. I don't need it since I have other note-taking apps, but I do like it and use it often. You can even share notes with other, more permanent note taking apps installed on your device.)
MySword Bible by Riversoft Information System (I've tried a half dozen or so bible apps and this one really is the best I've seen, so far. Can be a little complicated to use in the beginning, though.)
Wise Proverbs Daily Bible by Roboticode
Words of Jesus Daily Bible by Roboticode
Feedly (an excellent replacement for Google's RSS reader)
Amazon Kindle
XBMC (I use it primarily to watch tv shows and movies, but it's also a good music player)
Yelp
YouTube
I also will give honorable mention to:
Roku's remote control app
Buddhist Meditation Trainer by Spacebug
Diamond Breaker (simple, but addicting game)
Instagram
UberSocial (I only use it as a Twitter client...not sure how it works with FB)
Flipboard (can't touch Feedly, but it's pretty)
Spotify (if you're a premium subscriber)
Google+ (I actually like the tablet app better than the desktop site. Sucks on my Evo, though)
iHeartRadio
Stitcher
TuneIn Radio
StumbleUpon
That's my list, so far. By any chance does someone know of a good goal setting/tracking app? I haven't liked any of the ones I've tried so far.