Password protection

You can password-protect apps like iTunes so that a family member can't buy every  record with your credit card. Go to Settings, then General, then Restrictions. Press Enable Restrictions and type a password, then turn on the restrictions you want for the apps available. Note that this password is different from your iTunes password - you'll need to tap in both. 

Add photos to contacts

You can add photos to your contacts in the iPad's contacts app. Its easy - go to the Contacts app and pick a contact. Tap Edit then tap 'add photo'. You can then move and scale the photo easily, so it fits perfectly. Once you're happy just tap Use. Alternatively, you can use the Photos app as your starting point for assigning a photo to a contact. Open the Photos app, find a photo and tap the Options button then tap Assign to Contact. 

Add a Google Calendar

Want to add your Google Calendar to the iPad's Calendar app? No problem. In Settings open Mail, Contacts, Calendars. Add an account and tap on Other. Tap on Add CalDAV Account and enter your Google Account credentials (the Server is www.google.com). Exit the Settings app and tap on the Calendar app and all your events should appear. By default all calendars are displayed, but you can tap on the Calendars button to choose which ones are shown. 

Copy music/videos from iPad to computer

Sometime we lost iTunes library or want to copy files from other iPad back to computer, because iTunes prevents user do that, you need special software to bypass iTunes. I‘d recommend iPad Magic (Windows / Mac) to you, It is a life saver when

 Sending your iPad for repair.
 Backup song/video/photo to PC.
 Moving song/video/photo to iPod or a new iPad.
 Share your iPad song/video/photo with friends.
 Computer crashed..

iPad Magic = iPad Transfer/Manager/Backup + iPad video converter + DVD to iPad Converter. It's the ultimate solution to all your iPad ripping, copying, converting and transferring problems!

 Transfer movies and songs from PC to iPad, iPad to PC, iPod/iPhone to iPad.
 Backup iPad movies and music to iTunes (Newly supports iTunes 9.2) library.
 Rip DVD/CD and convert videos/audios/ISO images/IFO folder to iPad.
 Manage several iPod/iPhones simultaneously without conflict.
 Copy contents from other iPods without wiping their iPod library.
 Supports all iPad/iPod/iPhone models.
 Fully support latest iTunes and iOS. 

Take Giant Screenshots

Another oldie but goody that many that many people don't realize you can do in the iPhone OS: screenshot anything you're looking at. And keep in mind, when this happens on the iPad, it's at 768x1024 resolution—making it potentially a lot more useful in the full-sized monitor realm than iPhone screenshots.

Push the top (power) and home buttons at once for half a second. The photo will be stored in your photo library.

Import Free Books

The iPad supports the ePub format, and you can load these books simply by e-mailing them to yourself. Apple's iBooks app is your portal to reading and buying eBooks on the iPad—and it includes a section with a few free books. But don't forget, just like iTunes and the iPod can import and play music downloaded elsewhere, the iTunes and the iPad can import and display books downloaded elsewhere. And keep in mind, iPad only supports ePub (with or without DRM).

Your local library may be a great source for free ePub checkouts. Also, Project Gutenberg has 30,000 free ePub books you can download, all of which have fallen out of copyright. There's lots of good stuff in this collection if you read classics, and the project even has an RSS list for new arrivals.

If you want to convert PDFs and other DRM-free formats to ePub, you can use Calibre.

Change your Default Email Signature

The default email signature on the iPad says, ―Sent from my iPad.‖  It finds that to be a little boastful. To remove the Apple marketing and become like a real person, go into Settings and tap on Mail, Contacts, Calendars. Find Signature in the fourth section down. Type whatever you wish.