Nokia N9 and Nokia N950 Developer and Designer topics:

Nokia N9 UX Guidelines (Designers & Developers, start here):
https://www.developer.nokia.com/swipe/ux/pages/getting_started.html

Harmattan Icon Generator:
http://depot.javispedro.com/nit/hicg/

Develop for the Nokia N9
https://www.developer.nokia.com/Devices/MeeGo/

Meego 1.2 Harmattan Developer Library
http://harmattan-dev.nokia.com/docs/library/html/guide/html/Developer_Library_MeeGo_1.2_Harmattan_Developer_Library.html

Gain Root: devel-su | rootme
http://my-meego.com/faq/showquestion.php?fldAuto=2&faq=2

Intro to Nokia MeeGo 1.2 Harmattan Qt Quick components
http://www.developer.nokia.com/Community/Blogs/blog/kate-alholas-forum-nokia-blog/2011/06/23/nokia-meego-1.2-harmattan-qt-quick-components

Qt Quick Components - Define a baseline Item set as common API between different component style implementations
https://bugreports.qt.nokia.com//browse/QTCOMPONENTS-200

QtInfo Project - Download the Harmattan deb for Qtinfo
http://projects.developer.nokia.com/qtinfo

Ariya's Qt Code Samples
http://ariya.ofilabs.com/code

How To Enable Developer Mode, Become Root and Install Opera Mobile 11 on the Nokia N9
http://blog.wapreview.com/15748/

Connecting MeeGo Harmattan Devices to Qt (The first time, I had to re-do the steps a few times to get my Mac OS X machine and the N950 to talk properly)
http://doc.qt.nokia.com/qtcreator-2.3/creator-developing-meego.html

Using Maemo or MeeGo Harmattan Emulator (Sometimes the emulator will run for me on Mac OS X and sometimes it will crash, easier to deploy to N950 than use the emulator as of Oct 2011)
http://doc.qt.nokia.com/qtcreator-2.3/creator-maemo-emulator.html

Nokia N950 specific topics (some may be deprecated in Beta 2):

Migrating from N900 to N950
http://wiki.meego.com/Migrating_from_N900_to_N950

Nokia N950 - How To Remove Developer Edition Branding
http://www.meegoexperts.com/2011/08/n950-remove-developer-edition-branding/

Nokia N950 - How to Set Homescreen Landscape
http://my-meego.com/faq/showquestion.php?fldAuto=5&faq=1

Nokia N950 Keyboard Shortcuts:
http://my-meego.com/faq/showquestion.php?fldAuto=10&faq=1

The N950 supports some useful hardware keyboard shortcuts, including:

Ctrl + Q - close the current application
Ctrl + Shift + P - take a screenshot (this only works for some applications, see here for more details)
Ctrl + Shift + F - show / hide FPS (frames per second) indication
Ctrl + Shift + L - cycle through enabled languages
Fn (lower leftmost key with arrow) + Backspace - switches from to the previous screen (usually task switcher or app launcher view)
start typing in any of the home screens - launches Search application with the text you typed.

Additionally, there as some shortcuts useful for software developers:

Ctrl + Shift + T - shows/hides positions of some UI elements
Ctrl + Shift + S - shows/hides dimensions of some UI elements
Ctrl + Shift + B - show/hide borders
Ctrl + Shift + M - show/hide margins
Ctrl + Shift + N - show/hide names of some UI elements.

Nokia N950 OneClickFlasher for Firmware Version 39-5
http://harmattan-dev.nokia.com/release/N950-39-5/