Thanks to the rich and flexible real-time API offered by Instagram earlier this year, developers are able to pull in not only images from the popular photo-sharing service, but also tags, locations, comments and other data.

Since the API was released, we've seen an uptick in third party applications that utilize it, some of them more effectively than others. This brings the service beyond the parameters of its native iPhone app, which was previously the only way to view photographs published on Instagram.

Instagre.at

For all the buzz and excitement around Instagram, it still doesn't have one seemingly basic thing: an official Website from which one can view its content on more than a one-off basis. Since their API became available, a number of Web-based apps have sprung up. One of the more attractive-looking ones is Instagre.at.

Rather than trying to mimick the full-fledged Instagram viewing experience, Instagre.at simply lets you view your photo streams in a Cover Flow-style horiztonal slideshow, which can be advanced by scrolling sideways or using the arrow keys on your keyboard. It unfortunately doesn't appear to support swipe gestures on the iPad, but it's still viewable from the Web browser on tablets.

Instagre.at also shows which filter was used when composing the image and gives you the option of liking photos.

Gramfeed

Another way to view Instagram photos in the browser is a by using a Web app called Gramfeed, which we reviewed when it was first released. It comes equipped with a really nice UI that displays images laid out in a grid or list and plots them on a map as well. In terms of functionality, it comes much closer to the iPhone with the ability to like photos, comment on them and follow users.

Instagallery

Of all the ways to view Instagram photos on the iPad, Instagallery is perhaps the one that feels the most like an official app from Instgram, but it's not. Its elegant and barebones UI displays photo streams in one of two ways: in a grid that will look familiar to users of the official iPhone app, or in a way that better suites the tablet form factor: as a full-screen slideshow.

Whether its your own photos, a feed of your friends' images, popular photos across Instagram or any custom search for tags, Instagallery will display them as a slideshow that can be swiped through manually or played through automatically.

Instamap

Instamap is another attractive interpretation of Instagram for iPad users. You can view photos in a grid layout, per usual, but instead of the fullscreen slideshow view offered by Instagallery, it lays photos out on - you guessed it - a map.

This is a neat way to view Instagram content in a way that isn't possible in the service's native application. In addition to a large cluster of photos from my friends in Philadelphia and New York, I can see photos from friends and colleagues on the West Coast, as well as from people in my network who happen to be living or traveling abroad at the moment.

Instamap, as its name would suggest, is all about location. In addition to my own photos, friends stream and tag-based searches, I can subscribe to locations around the world, viewing Instagrammed photos from other cities in real time.

Things get really interesting when I subscribe to locations that are more granular than the city level. I can not only view photos taken across my native Philadelphia, but can drill down further to my specific neighborhood, an intersection or a particular business or venue nearby.

Instaframe

If Instagallery and Instamap had a baby, it would be named Instaframe. This stripped-down iPad app combines a sideways-scrolling slideshow layout of photos with a map-based view showing where each photo was taken. That's pretty much it. The functionality is pretty minimal in this one, but it remains a nice way to view Instagram content on tablets.

Flipboard

While it's by no means the app's central purpose, Flipboard does let you plug in your Instagram account and view your photo streams through the much-beloved social magazine application for the iPad. Viewing Instagram photos on Flipboard is exactly what you'd expect: it lays out your photo streams much like a digital magazine, through which you can flip by swiping your finger. It's a nice touch for an app that already does so much and the Flipboard UI is an especially pleasant way to view photos. The integration supports liking, commenting and sharing images via social media and email.