Let's start one of these.. We have great apps too!!
For inormation completeness, Accuweather is pretty great however the app performance is pretty sub-par and it loads really slowly.
As far as a mix of good looks, great performance and even better Live Tile, I have to give it to WeatherFlow. Now it isn't free for about 15-20 seconds with it and you'll want to pay the cost of it.
Games - There's a bunch of Xbox Live games on the platform. A number of decent ones have had price drops to 0.99$ recently. You can find em listed here - http://www.wpcentral.com/angry-birds-and-six-other
Some of my personal favorites
Supports every courier under the sun. Very handy when you're shipping/receiving a package and want to track it.
Excellent News Reader with a very responsive developer to new features
Handy for countdown time
Great for finding out info about Phone Solicitors
Remote Desktop 7
Excellent Remote Desktop Client for Windows Phone 7, worth the cost if you need it
Keep Sensitive Data Encrypted and Password Protected
My Starbucks Card
For the odd times I get a Starbucks card
It's in Beta so you want see it in the Marketplace but here is the link
Not as pretty as Weather Flow but has lots of info on one two pages, fast syncing
I'm sure everyone knows this, for finding that song you are hearing
Old School RPG, lots of phone, there is a free/paid version
If you like Tower Defense games, it's awesome!
Sid Meier's Pirates
One of my all time favorates but they have to fix load times....Worth checking the trial
NES Emulator, needs work but it's free and it can play games
For those brain dead subway ride homes
Good RPG Action style game
Rise of Glory
Arcade Flight Simulator style combat
Apps I like:
WeatherFlow, WeatherLive - both have nice live tiles.
BBC Mobile - Also a nice live tile
Prime TV - Keep track of your favorite TV shows
Fuse - RSS reader
Sports Now - Get your NHL, MLB, NBA and NFL scores, works very fast
WP Central - Windows Phone news
Executive Caddie - Golf app
MetrofaceLift - get nice wallpapers
MyEncyclopedia - nice wiki app
PrimeTube - great YouTube app
SkyScanner - get flight prices
Translator - excellent language translator from MS
WP Shortcut Tile - ex: add a tile to get to your Bluetooth and Wifi settings quickly
Games: (I noticed a nice performance bump going from Focus to Lumia)
Fable Coin Golf
Alchemic Phone 7
Words by Post - Plays cross-platform
Some of my apps will echo those already listed, but my most used apps are:
Weave - News/RSS reader, very quick to update even with hundreds of unread news items and formatting of articles is generally very good
ESPN - Not much to say, great sports app for checking scores and game highlights. My only wish is that they can add a Live tile/notifications or the ability to pin our favorite teams.
PrimeTV - Nice TV app to keep track of your favourite shows. Good Live tile which updates to your next episode throughout the week.
Carbon - Twitter client. I've used Birdsong and Mehdoh and found both nice as well, but I like Carbon the best for it's speed and features (in line images are cool).
4th & Mayor - Foursquare app, made by a MS employee and has better performance that the official app (although arguably not as nice looking).
WeatherMaster - Nice weather app. As far as I know it is the only app which has a GPS location that can follow you on the Live tile which is handy during the week where it will switch from my home to work locations automatically.
Parcel Tracker - Track delivery of packages from any shipping service with live tile and notifications.
MyStocks Portfolio - Stock tracking app with Live tile for my employers stock price (Free version).
Also, a few of my favorite games at the moment:
Wordament - Highly recommended, free and soon to be Live enabled as well
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