[G2 and Desire Z General] Ghostcreamy:
I thought I'd share everything I've learned regarding Android & the T-Mobile G2 over the past 2+ weeks (thanks XDA!). I'm amazed at how many people don't read these forums - they simply blurt out their questions. Well follks, here's what I've picked up by reading reading reading & exploring exploring exploring. Hope this helps n00bs and leets alike.

Android

Press & Hold HOME to see multitasking applications sorted by most recent

Press & Hold SEARCH to activate Google Voice Actions (or VLingo if installed)

Long Press keyboard keys to see alternate characters

Tap Dots near the Dock Bar (bottom set of icons) to shift screens

Assign your Power Button to 'End Calls' via Menu >Settings >Accessibility > Check "Power button ends call"

Add 'Power Control' Widget to easily enable/disable your WiFi/BlueTooth/GPS/Screen/Auto-Sync

Using Volume Control buttons, you can put the phone into Silent or Vibrate modes

You can add Shortcuts to your most used contacts & it will give an icon that lets you access Call/SMS/Email/GTalk/Facebook

Keyboard Tips

Double Press ALT for Num/Symbol Lock

Double Press SHIFT for Capitalization Lock

Hold ALT & Long Press physical keys to see alternative characters

Map Application Shortcuts such as Search + G to launch Gmail. Located under Settings >Applications >Quick Launch

Menu +A(Select All), +C(Copy), +V(Paste), +X(Paste)

Menu +F(Find), +S(Share)

(G2 Only?) Reboot, Press and hold Power + Volume Down + trackpad

(G2 Only?) Use LauncherPro to Assign 'Activities' to the Quick Keys such as Compose SMS or Tweet

(G2 Only?) Press & Hold the Camera Button to activate the Camera

(G2 Only?) While in Camera Mode, gently press the camera button to auto-focus

Miscellaneous

Install a custom launcher like ADW or LauncherPro

- Tip 1: If you get LauncherPro, I encourage you to explore the 'Swipe' feature by Long Pressing any icon in the Dock. Allows for two actions!

- Tip 2: My personal favorite is when you hide the status bar and set the HOME button to display notifications when you press it (Only possible if you make LauncherPro default launcher)

- Tip 3: Long Press an Application & when the Trash Can Appears, Hold over the Trashcan to get an Uninstall Option

Use Tasker to automate things on your phone

TeslaHD will turn your phone's LED into a Flash Light or Strobe Light

AppBrain + Fast Install is excellent for exploring apps from the comfort of a browser (also lets you set backgrounds)

- This App also makes it easy to restore apps if you didn't remember to set your 'backup' as automatic when configuring your phone

VLingo is a great alternative to Voice Actions if you're not on 2.2 OR you want deeper integration with Twitter/Facebook/Foursquare

Google Gestures is a great app to assign to a secondary swipe (see LauncherPro) & is handy when voice doesn't work and you can't easily type

DolphinHD is a great alternative browser that has three great features: Tweet a Page (with Title & Link), Desktop Mode, and Google Mobilizer View

Dial 611 to get to T-Mobile Customer Support (not always clear to new subscribers)

Best Keyboard for two-finger text input is SwiftKey. Swype is good if you practice with one finger.

Other Great Apps to Consider

Evernote (for note storage)

Dropbox (for access to files from your desktop)

Fast Reboot (for a heavy handed, kill all apps when you notice slow performance)

Dato GTasks (simple, easy to use app that integrates with Google Tasks)

NewsRob (elegant RSS reader for Google Reader)

Smooth Calendar (nice calendar widget that shows more than the default Calendar widget)

Xtremelabs Speedtest (helps you test for HSPA+ speeds)

Twicca (better than the standard Twitter App & very beautiful. Easy to map Tweet-Activity to a G2 Quick Key)

Chrome to Phone (possibly my favorite app once I learned how to use it. Great for a variety of needs so I encourage experimentation)

Optimize Your G2

Go to SETTINGS > APPLICATIONS > DEVELOPMENT and enable USB DEBUGGING

Search the Market for "Visionary" and Install (advice: Reboot & then run it for the first time) By default, it will run automatically on boot each time.

- Note: If you want to remove ROOT, visit APPLICATIONS > MANAGE APPLICATIONS > VISIONARY and press "Clear Data". Then re-run & turn off Root-on-Boot or just Uninstall.

Search the Market for "ConnectBot" & Install. Run Connectbot & press the down-arrow next to "ssh" to choose "local" & press Enter (no Nickname needed)

- You will be presented with a command line prompt of "$" & yes, it will be VERY TINY on your screen. Simply type "su" (no quotes) to gain super user.

- Read the first post to determine which items you want to permanently disable (essentially remove) from your phone: http://xdaforums.com/showthread.php?t=809231

Visit the market to download "Startup Cleaner 2.0" by Bright Wallace. It will allow you to prevent items from starting up. The software is buggy, but works better than anything else I've encountered.

- Tip: Use the 'Batch Prevent' to prevent all apps from starting, then exit the app. Run the app again & then toggle the apps you want to start by tapping them. Otherwise, the app is very unresponsive when trying to manage apps on an individual basis. You may need to re-run Visionary after you've allowed it to run on boot via Startup Cleaner.

Setup Wifi Tethering

Once you have Root & SuperUser, use your browser to visit http://code.google.com/p/android-wifi-tether/downloads/list & download the most recent version of "Wireless Tether".

- Once downloaded, run it to install. If you have trouble with this, I recommend using Chrome-to-Phone & simply right-click the file link to choose "Chrome-to-Phone"

After successful installation, run the Wireless Tether app. Recommend changing the SSID Name (name that appears).

- Note: Multiple people report issues with WiFi Encryption, so I recommend SETTINGS > ENABLE ACCESS-CONTROL. Your phone will log when something tries to connect to it & then you can "allow" by choosing MENU > ACCESS CONTROL and clicking the checkbox next to the device you want to allow.

{Update} If you're feeling adventurous, check out this article on how to use Tasker

http://androinica.com/2010/08/19/9-ways-to-make-android-automatic-with-tasker/

{Update 2} Long-press App & dragging over trashcan for uninstall is a LauncherPro feature, not android. Thanks to tekkaman_01 for the note!

{Update 3} Removed "When screen is locked but keyboard is open, you only have to press a key to unlock" because it isn't a consistent experience. Not sure what makes it work sometimes.

{Update 4} Added two sections: Optimize Your G2 & Setup WiFi Tethering. Small formatting changes to previous entries.