GENERAL
If you're scrolling through a long document/page in an application - if you tap the bar at the top of your screen containing the time and battery, the application will automatically scroll up to the top of the document/page.
To take a screenshot of any screen of your iPod (including the lock screen), hold the power and home buttons and release them. A white flash will appear on screen and a screenshot will appear in your Photos application.
If your iPod is frozen and will not respond, you can force reboot by holding the power and home buttons until your device turns off. Please note that this is not recommended and is the equivalent of pulling the cord out of your computer to turn it off.
Need a spare cleaning cloth for your touch, or an extra cloth to rest your iPod touch on while at work or school? Just go to your local vision care store (or pharmacy) and get an eyeglass/sunglass "cleaning cloth". Cheap and works great!
If you wish to change your device's root SFTP password, open Terminal and type 'passwd'. You will then be prompted to change your password.

MEDIA
Double tapping the home button in any application, or with the screen off will bring up the music controls.
When watching a video, tap to bring up the onscreen controls. When you are done watching a video make sure you press done so your progress will be saved.
When listening to an audiobook, iTunes and your iPod create a new chapter list unrelated to the subject of the book. It's accessible using the same control used for viewing audio tracks (upper right of screen).
When playing media, press and hold the forward button to incrementally increase the speed of playback. When the media is paused, holding the fast forward button will make the media play slower.
When listening to music, double tap the album artwork to have it flip over. You can then view the tracklisting of the album.
If you pull your headphones out of the socket, any currently playing media will pause.
If you would like to view the lyrics of a song (if you've added lyrics), by tapping the album art on the Now Playing screen.

BATTERY
Turn off WiFi to save battery power when not in use.
JB ONLY: Turn off SSH via SBSettings.
Make sure to completely close apps when you are done with them to save battery power. This is accomplished by pressing and holding the home button for approximately five seconds. This boosts battery life big time if you run lots of different apps all the time.
You can charge your iPod Touch from any fully powered USB 2.0 port. A PS2 does not have a fully powered USB 2.0 port. Ports that will work include a computer, printer, or a media centre. The device does not have to have iTunes installed to provide power to your iPod Touch.
To improve battery life, turn down brightness through the Settings application.

HOME SCREEN
If you would like to rearrange your Home Screen icons, tap and hold an icon until they all start to wiggle. Drag the icons around to rearrange them, and when it is satisfactory, press the home button.
Websites without an icon will just be a screenshot for webclips, for websites like this zoom into an area of the site you would like the webclip icon to look like... ex. zoom into the website logo and that will be the webclip icon.
Press the home button while on the home screen, and it will return to the initial home screen.
Instead of sliding across the page, tapping imediately left or right of the page dots on the Home Screen and Weather will move to the next page.

THEMES: JAILBREAK ONLY
If you want to set a picture as a permanent background (and not only in the "wake" screen) Set the picture as a background in settings or directly from the picture gallery. Then, open Winterboard and tap User Wallpaper.

KEYBOARD
When typing a lot of text in Safari turn it to horizontal view. The keyboard will be bigger and you can get a better grip of the Touch while typing with two thumbs.
When typing, if you press the space bar twice after a word it will insert a period and another space.
When using the keyboard, if you hold the delete key down for about 3 seconds it will change from deleting letters to deleting words.
Holding down letters on the keyboard will pop up the accents/symbols associated with those letters. Once it pops up, slide your finger over to the accent/symbol you like.
When typing if you want to add something from the numbers keyboard just hold down the numbers and slide your finger to the number or symbol you want, and release. It will take you back to your letters keyboard. This way you dont have to tap numbers, tap your number, then tap numbers again to go back. This also applies for using the 'shift' key to apply capital letters.
Make a spelling mistake? Press and hold the word you spelt wrong and a magnifying glass will appear. Slide your finger back and forwth to move the cursor.

SAFARI
When in Safari, if you are presented with a link, hold your finger over the link, and a bubble will appear showing the URL that the link is tied to.
In Safari since you can't open links in a new windows, you can open a new page, tap the bookmarks icon, tap the history folder and direct yourself to the last page you were just on and tap the link from there. You can also use a javascript bookmarklet called Tabulate.
When you're on a website that has a frame or an iframe with scrollbars in it, use two fingers on that frame to scroll that window and back to a single finger to scroll the whole page.
If you would like to save an image from the web, simply tap and hold the image to save it.
In Safari double tap to zoom in or out. You can also "pinch" (putting your thumb and index finger on the screen and pinching in and out) to zoom in Safari, Maps, and in Pictures.

OTHER APPS
Whilst in Mail's inbox view, sliding your finger from left to right on a message the 'delete' button will appear. This also applies in the list view of the Videos application. You can also delete Mail in bulk by tapping 'edit' and selecting the Mail you want to have deleted.
In Google Maps, double tapping zooms in as expected, but single tapping with two fingers zooms out.
The 'Notes' application is an easy way to draft mail. The 'mail' icon provides a link to iPhone's Mail and saved contacts.
To use a scientific calculator, simply enter the Calculator application, and turn the device sideways.

Some information taken from original thread posted by thomashayes. Thanks to everybody who contributed to that original thread. I'm sorry that I am unable to accredit you for your tips as there were so many wonderful tips & tricks out there.

Quote [Originally Posted by SkylarEC]