Social media management service HootSuite, which boasts some 4 million users and is employed by no less than 79 of the world’s Fortune 100 companies, has just updated its App Directory to include apps for the popular photo sharing service Instagram, as well as SlideShare, Zuum and Edocr.

Hootsuite, for those who didn’t know, is designed to make social media campaign management easier by providing a unified interface for multiple social networks, including big guns Twitter, Facebook and LinkedIn. While these three networks are the only defaults, users can add dozens more services via the HootSuite App Directory, allowing them to manage everything from Flickr to YouTube through the same interface.

The integration of Instagram is obviously a big update for HootSuite, as it continues to be one of the fastest growing social services around, adding as many as five million new users each week.

The new app will allow users to search for and view photos, like them and share them through other social networks, add comments, and read what others have said, directly through the HootSuite interface.

SlidesShare too, is a big addition, albeit an expected one. The platform, which is used for sharing PowerPoint decks, presentations and other files, was snapped up by LinkedIn earlier this year, something that made its integration into HootSuite only a matter of time. Users will now be able to find, upload and share content to and from SlideShare using the HootSuite interface.

What is perhaps more interesting is the addition of Edocr and Zuum to HootSuite.

The inclusion of Edocr especially, is highly unusual given the fact that the business document sharing website currently only has a few thousand monthly users and very few readers are unlikely to have even heard of it.

For its part, Zuum could actually be considered a rival to HootSuite, as it offers a platform for users to manage their social media strategy. One of the unique features of Zuum is that it’s able to come up with content-posting suggestions  for users, recommending blog posts and articles it deems likely to be engaging. HootSuite users will now be able to access all of Zuum’s social metrics tools directly from its main interface, searching for the best performing Facebook posts in terms of likes, comments and shares.

The new apps are available to use now in HootSuite’s App Directory, and the good news is that the company is not about to rest on its laurels just yet. Listed in the App Directory, the likes of Blogger, Chatter, Disqus and Yammer are all soon to be made available through HootSuite.