Apple sells a very nice Camera Connection Kit for iPad as well as an Lightning SD Reader/USB adapter for the 4th Gen iPad and iPad mini. These adapters allow you to bring in images from your regular camera into your iPad. Great! However, the problem with this is that if you bring in say 100 pictures and then decide to delete say 50 of them after reviewing them, currently there is no way to do that other than one by one. Unfortunately there is no Select All command in the Photos App on the iPad. You have to tap them one-by-one to select them to delete them. Anything over 10 becomes a chore. Luckily there is a way to do this if you have a Mac. Just plug your iPad into your Mac via the USB sync cable. Quit iTunes if it launches as this tip has nothing to do with iTunes or syncing.
Now launch Image Capture from your Applications folder. It should see your connected iPad and the images on it. You can now select the first one and scroll down to the last one and Shift-Click to select them all. Click the Delete icon and you can delete all of the selected photos at once.
Also Image Capture is a great way to import your iPhone, iPad and iPod touch photos and videos that you took, directly to a folder and have them delete after import all at the same time. This bypasses iPhoto.