Keep in mind most of these are specific to Android 2.3 Gingerbread. Here's my list:
1. Tips
- Visual cue for scrolling: When you are in a scrollable list (like your Gmail inbox) and you reach the end of the list it shows an orange hue—a visual cue that you can’t scroll anymore.
- Notification bar icons (Wi-Fi, network coverage bars, etc.): Turn green when you have an uninhibited connection to Google, white when you don't. Hint: if you're in a hotel or airport using Wi-Fi, the bars won't turn green until you launch the browser and get past the captive portal.
- Voice actions: Tell your phone what to do by pressing the microphone icon next to the search box on the home screen, or long press the magnifying glass. You can tell it to send an email or text message (“send text to mom, see you for pizza at 7”), call someone ("call mom"), navigate somewhere (“navigate to pizza”), or listen to music ("listen to Mamma Mia").
- Find things you’ve downloaded from your browser: Your downloads are now neatly collected in a Downloads manager, which you can find in the apps drawer.
- Turn a Gallery stack into a slideshow: In Gallery, when you are looking at a stack of photos, put two fingers on the stack and spread them. The stack spreads out and the pictures flow from one finger to the other, a moving slideshow that lets you see all of the photos.
- Walk, don’t drive: Once you’ve gotten directions within Google Maps, click on the walking person icon to get walking directions.
- Easy text copy/paste from a webpage: To copy/paste from a webpage, long press some text, drag the handles around to select the text you want to copy, and press somewhere in the highlighted region. To paste, simply long press a text entry box and select paste. Gmail is a bit different: you need to go to Menu > More > Select Text.
- Turn your phone into a Wi-Fi hotspot: Go to Settings > Wireless & Networks > Tethering & Portable Hotspot. (You may have to pay extra for this feature.)
- Look at Maps in 3D: With the latest release of Google Maps, you can now look at 3D maps. Tilt the map by sliding two fingers vertically up/down the screen, and rotate it by placing two fingers on the map and sliding in a circular motion, e.g., from 12 and 6 o’clock to 3 and 9.
- Cool shutdown effect: When you put the phone to sleep, you’ll see an animation that resembles an old cathode tube TV turning off.
- Shift+Key to capitalize a word: In Gingerbread (and supported hardware), you can Shift+Key to capitalize a letter instead of going to a separate all caps keyboard.
- Auto-complete: The space bar lights up when auto-complete can finish a word.
- Quick replace: Tap on any previously typed word, then tap on a suggestion to automatically replace it with the suggested word.
- Easy access to special characters (like numbers, punctuation): Press and hold any key to go to the special character keyboard. You can also press and hold the "," key for an extensive punctuation keyboard.
- Angry Birds: Popular game that lets you knock down blocks by slingshotting birds.
- Astro: Awesome file explorer app. Browse and access the directories on your phone, and take full advantage of its capabilities. Great if you’re a power user.
- Chrome to Phone: This one is really useful for Chrome users. You can send anything you browse on your computer to your phone. So if you are heading out to a restaurant or party and look up directions on your computer, just click the “send to phone” button (requires Chrome to Phone extension) and that exact page will open on your phone. Same with virtually any webpage.
- Flash: Install from Android Market to watch Flash videos embedded throughout the web. Runs even better on Gingerbread.
- Fruit Ninja: A juicy action game that tests your ability to smash flying fruit. A fun time-killer on the bus or train.
- FXCamera: Popular photo sharing app with slick effects and filters.
- Google Maps: Use your device as a GPS navigation system with free turn-by-turn voice guidance, and take advantage of other Google Maps features like Street View, Latitude and Places.
- Instant Heart Rate: Measure your heart rate using your camera.
- Phoneanlyzr: Track your phone usage: who you text most, call most, average call length distribution, etc.
- RemoteDroid: Control your computer from your phone. Gives you a mobile wireless mouse and keyboard. Great if you’re using your computer for music or movies.
- Shazam: Identifies virtually any song you are listening to.
- SoundHound: Record a snippet of a song and get it identified instantly. You can even hum (if you can carry a tune!).
- Tango: A free, high-quality video call app that works on both 3G and Wi-Fi. If your device has a front facing camera (e.g., Nexus S), you will love this app.
- YouTube: New UI. Plus, portrait-mode player, and view comments and drop-down box video information
Time is precious and all 
