This is a difficult question. Hard to choose first, so here's a list of the first apps I'll be loading on my device.
My first thought was to try Netflix.
But I've also wanted to try out twit (free) for the TWiT network
Then there's 4th & Mayor (a foursquare client)
Also thinking about Fruit Ninja
And there's the obligatory Xbox Live Extras
Of the top of my head, those are the first apps I want to install. Any suggestions?
Keeping in mind that I already have a number of apps (though I haven't gone crazy since this phone is for development).
4th and Mayor is the best 4Square app. Been using it and love it.
Geocaching - if you don't know what geocaching is, go to geocaching.com and learn more. They have a very good app, and once Mango gives access to the compass API, the app will be all you need for geocaching. Now you can do it, but it will be easier once the compass works.
The Weather Channel - has a live tile, too.
MoTweets - there is a free and a paid version. Take your pic. I think the functionality is the same, but the free version is ad supported.
I'm not a gamer, but I did download a couple. Harbor Master is the only one I've bought.
Final Approach - you're an air traffic controller.
Krashlander - this game has actually earned its developer more than 18,000 dollars by his wise use of ad banners in the game during non-play time, but removing them during play. He also earned an undisclosed (by contract) amount from one of the handset manufacturers who is going to put the game in their devices.
KeyRing - take a picture of all those discount cards you carry, and let the cashier scan your phone screen, thereby thinning your wallet, and allowing your back to heal from sitting crooked all these years.
Amazon Hunter - a free app developed by an acquaintance - take a picture of the barcode on an item, and get back pricing from Amazon.
Gas Buddy - map gas station prices based on your location. Earn entries in a drawing for free gas by reporting gas prices around you.
Netflix - yes, you can stream movies on your phone. SWEET.
Shop Savvy - take barcode pics and get results back on prices both online and in your area.
Where's my car? - mark the GPS location of your car, as well as take a picture of where it's at. Good if you find yourself in places where you are unfamiliar and have to go some distance from your car.
PlusPoints - for those of you like me, who are on Weight Watchers, this app calculates and tracks your points (this is MY app - my first to the Marketplace)
Actually the Trophy is for my Wife (Trophy = Wife, get it - snort, snort)
I suspect that Fruit Ninja will be her first actual $$$ pruchase. But Her is the list of my favortite apps that I've been using on my Samsung Focus:
Weather Channel App (free)
USA Today (free)
Geek Peek (free)
WP7 News (free)
Adobe Reader (free)
Amazon Kindle (free)
Gas Buddy (free)
i-Clickr ($9.99 but I do a lot of Powerpoints)
The Onion (free)
TuneIn Radio (free)
WebStats Mobile ($4.99)
Flowerz (free for Samsing Focus, don;t know for Trophy yet)
Fruit Ninja ($2.99)
I Dig It ($2.99)
iBlast Moki (was Free for Samsung Focus, priced at $2.99 now)
Parachute Panic ($2.99)
Attack from the Dead ($.99)
Bullet Overload ($.99)
Chicks and Vixens ($1.99)
Popper2 (free or $.99 no ads)
Worm Hole (free)
As you can see there is a lot of free items there, though many of the better games carry a price. But certainly all of the ones mentioned are pretty good.
My first app will be the MTA App, if you are not from NYC you probably asking WTH is MTA App..It is to navagate the NYC Subway, a must have if you live here. My 2 is Turn by turn Nav that was just published at the MP and then I will see what else.
Been wanting to play it since they showed screen shots after announcing wp7.
Watching shows on my phone, then continuing on Xbox has really impressed my boys.