In settings > sound > device vibration, you can select a different pattern of vibrate, or just make your own by touching create!
In app drawer > widgets, Sammy added a widget to use flash as a flashlight, and a widget to turn the entire phone into negative colors.
You can set the brightness in the majority of stock apps (i.e. the browser) to be app specific, instead of just setting a brightness for the entire system. For example: set the brightness to auto in the system settings, then open the stock browser > brightness and colors, and set it to high. Now the system will have auto brightness, but it will always go to high/bright when you are in the browser!
If you go to Phone > Logs > call logs, you can long-press a number (like that telemarketer you always reject) and select "add to reject list" to have the phone automatically reject the call every time. You can also unblock the number in case you change your mind.
In the stock messaging app, you can go to settings, and on the top you will find options to change the background and bubble style of the messages.
Samsung's S-Voice can do complex mathematical equations for you, then show them in different answers. For example, open S-Voice, and ask "how many inches are in a mile?". Or "what's the square root of 543,636?".
In settings > security > lock screen options > shortcuts, you can change what shortcuts appear on your lockscreen, or take them out altogether.
On the headphones that came with your device, you will see a single button and the volume controls. One press of the single button will pause the music, two presses in quick succession will skip to the next track.
In settings > wallpaper > home & lockscreen, if you select a live wallpaper, it will show as your lock screen as well. It will deactivate the ripple effect though if you have it active.
You can also use pop-up play on streaming online videos as long as they're not YouTube videos, and as long as you use the stock video player to stream them.
Pictures come out better with the camera if you hold the camera button and let it focus before the shot, rather than just pressing it after touching the focus box.
The stock browser has "incognito mode" just like Google Chrome! You can access it by opening the browser, the touching the top right corner to see open windows, then touching the incognito icon. While you're incognito, no history/cookies/or form data will be saved.
While you are on a call, on the screen where the contact picture is displayed, there is a speaker icon in a bubble. Touch it to increase the call volume past the maximum setting. It works on speaker or on headset setting.
*edit*
If you're not rooted, but want to get rid of those pesky bloatware apps, go to settings > application manager > all, and select the app. Within those settings you can clear the information the app has, then disable the app with the top right button. You may need to uninstall updates before it says disable app though... you can also go to the app drawer, hit menu, then select "hide apps" to hide the bloatware icons you've disabled.
That's all I can remember for now, I'll add more soon. OP you should copy and paste everything everyone adds to the OP so it can stay updated ( just a suggestion for organization).
Great thread lets keep it alive!
-Z
Sent from my Sprint Galaxy SIII using XDA Premium