It's been just about a year since Edge started to support extensions. Since that time, the library has grown. It's not nearly as extensive as other browsers, but as you can see here, it's got the essentials.
Pocket is my go-to tool for storing all my daily reading. Now, you can use Edge and still store to Pocket. Very cool.
This is far cooler than you might expect. It lets you remember products from all across the web and then gives you price comparisons and updates. It could save you a bundle.
Tampermonkey is not for everyone. But if you want to customize certain webpages to your liking, Tampermonkey is the tool to do it. Non-geeks need not apply.
Evernote is an amazing product. Evernote Web Clipper lets you easily grab pages and selections for storage in Evernote.
Do you value your privacy? Do you want to know who's tracking you? Do you want to prevent your online steps from being shared with advertisers? If the answer to these is yes, then install Ghostery.
Select what you want to be translated or let Translator translate an entire page. It doesn't do Conversational Klingon, but otherwise, it's a universally useful tool.
Reddit is...what it is. Amazingly active, the site's interface leaves something to be desired. Reddit Enhancement Suite helps that out with a pile of features too numerous to list here.
If you want to connect to Microsoft's online office suite, this extension is a big help. Not only will it get you to online versions of the famous Office suite, it will also open recent files quickly.
This is another web clipper, but if you're going to use a browser, you want clipper support. OneNote is getting more and more compelling, and it's no surprise Microsoft has ported the clipper to Edge.
Edge has password add-on support for a number of password managers, but Lastpass is probably the most popular. It integrates nicely with all your other devices, so it's a must-have extension for Edge to be taken seriously.