Eye-Fi SD Card. The wireless storage card broadcasts its own wi-fi network — and even does antenna triangulation to geotag images. It's also an SD card, so it will fit and work in most cameras — compact shooters and DSLRs alike. A camera compatabilty chart can be found here on their website (I personally use the Pro X2 Eye-Fi card).
Once you get the card, you'll want the free app on your Android Tablet or iPad (or even iPhone). You'll then need to open the app and perform an initial setup which pairs the card with your device — this adds an Eye-fi profile and lets you pick what media types you want to stream.
I choose to only stream "Photos" (which means only JPG files), not "RAW" files, as those are too large to stream quickly.
I then simply turn on my camera and go to Settings -> Wi-Fi on the iPad and choose the Eye-fi Card network. If you don't see the network, make sure your camera is set up to broadcast the signal. For my Canon, I had to Enable Eye-Fi transmission in the Menu Settings.
Once connected, open the Eye-fi App and direct mode should be initiated. Now as you shoot photos (you'll need to have your camera set to record RAW + JPG, or JPG only if you choose to just stream the "Photos") the images will be sent to the iPad. It may take a moment for the first image to transfer, but then subsequent images begin to show up rather quickly.
That's really all it takes, and you're now setup to stream photos from your camera to your tablet, iPad, or smartphone yourself. The neat thing about doing this on the iPad is if you have Photo Stream enabled, then you'll be able to see those same images on your iPhone or other iOS devices as well. It's perfect for sending in an email, or attaching to my Twitter or Instagram messages.
This is an essential tool in my shoots, and recent updates have made the Eye-fi card and app something I can always rely on. (Images: Chris Perez)