1) Facebook.com (DA 100) This is one of the most trusted and most used sites in the world, so it's a given that your main site gets a link from Facebook. Whenever a business starts out, they always build a Facebook page and so should you.
2) Twitter.com (DA 100) You can't say enough about Twitter. Creating a profile is super easy, and so is putting a link on here too. Another massively popular major website, this is one of the most trusted platforms you will come across.
3) YouTube.com (DA 100) Being owned by Google, creating a YouTube channel not only allows you to put 1 backlink on there but up to 5 on the channel page. This is great to link to your website as well as other social media sites, such as the ones listed in this post.
4) Google.com/business (DA 100) If you are doing local client SEO consulting, every business should be setting up their Google My Business page. What better way to get a link than from Google themselves. Make sure you fill out all of the information perfectly.
5) LinkedIn.com (DA 100) The most popular website for networking and meeting other business-minded individuals, it's no surprise that this one is a domain authority 100 website. Millions of people use this seed site to not only meet others but to link out to their own websites.
6) Pinterest.com (DA 100) This one came onto the scene and has been a major powerhouse as far as social media sites go ever since. When you create your profile, you can put your link back to your main site, as well as getting it verified too. Make sure to pins your other sites as well.
7) Reddit.com (DA 99) One of the most popular social booking marking sites, Reddit gives you the ability to create a free profile account. The thing here is to create a bookmark of your main site, getting you a backlink from a high DA website isn't all too bad.
8) Stumbleupon.com (DA 98) You can tell by now, social bookmarking websites are not only very popular, but very high authority. The thing about this site is to add your other social media profiles to it, as well as bookmark your main site, this gives you tons of links.
9) Vimeo.com (DA 98) One of the most popular videos sharing websites in the world just behind YouTube, Vimeo is great because they allow you to add a ton of backlinks to your profile, not only do you want to link to your main site, make sure to add all of your other profiles too.
10) Tumblr.com (DA 98) Some might call this a Web 2.0, but it's no question that Tumblr is a huge powerhouse. Create a profile, and start adding links out to your other profiles, this gives you a huge social stack from a major website (Being owned by Yahoo is just an added bonus).
11) Instagram.com (DA 97) Now owned by Facebook, Instagram is the main app you have on your smartphone that helps you add filters to your photos and make them look amazing. At a DA of 97, create a profile on your phone, and make sure to add your backlink on the website.
12) Disqus.com (DA 97) Disqus has come on the scene to be a contender as the main commenting system on websites such as Wordpress, replacing the default commenting system. Your Disqus profile gives you a chance to place your backlink on this great website.
13) SlideShare.net (DA 95) This fantastic site for sharing such things as your powerpoint and keynote presentations, Slideshare also allows you to link back to your main site, as well as link out to your Twitter, Facebook, and LinkedIn profiles.
14) Yelp.com (DA 94) One of the most popular online review websites, you cannot have a local business without having a Yelp profile. Yelp lets any business set up a free account, and put up company and business information such as the link to your main site.
15) Dailymotion.com (DA 94) Another one of the top video sharing websites in the world, Dailymotion, similar to what appears on the YouTube channel page, you can add 5 other social media websites, so make sure you add your main site, along with 4 other social profiles too.
16) Soundcloud.com (DA 93) Want to get a backlink from this powerhouse audio sharing site? Well, how about lots of links instead! SoundCloud is great for adding a ton of your other social media profiles, this makes your social stacking that much more powerful.
17) Diigo.com (DA 92) This popular social bookmarking website gives you multiple opportunities to link back to your websites, by offering a company page as well as a profile page, that you can start to bookmark all of your social sites and your main site too.
18) Scribd.com (DA 92) This super popular book reading website offers a powerful high domain authority link to point back to your main site or another social profile site for that matter. Scribd is one of those sites that every SEO should use to help with their rankings.
19) About.me (DA 90) As soon as you start your backlinking campaign for yourself or your client's site, you should jump onto creating your About.me profile. A really neat website that not only lets you display your talents but also links back to your many other social properties.
20) Moz.com (DA 88) We all know Moz. We also all know Moz's very popular Open Site Explorer which gives us all of these DA values in the first place. But did you also know that your Moz profile is a great place to link back to your website from, and your Twitter, Facebook, etc?
21) Storify.com (DA 87) This big content curation site lets you link back to your website from the details section of your profile. Whats better is that you can bookmark tons of your other websites as well creating this monster page of links back to all of your important properties.
22) Crunchbase.com (DA 86) Whether it's your own agency business, or a client you are working for, get a company profile on here for sure. You not only can add information like products, team members, and more, you can also get a juicy backlink from here as well.
23) Scoop.it (DA 86) Setting up your account on Scoop.it is super easy, and gives you the chance to get your other social profiles bookmarked on the site, giving you a power domain stacking monster. Make sure to add your main site to your profile too.
24) Instapaper.com (DA 85) I love Instapaper because it is one of the cleanest and minimalist websites bookmarking tools out there. But under that top layer of skin is a super powerful site that gives you the ability to get all of your links clipped and on there.
25) Wattpad.com (DA 79) Not many people have heard of Wattpad, but for a DA 79, this site is not bad after all. You see, its a huge community of readers and writers, and also lets you create a profile with a nice little backlink for your website. Now wasn't that easy.
26) Envato.com (DA 78) Unquestionably one of the most popular and best online marketplaces for plugins, themes, videos, stock images, and so much more, this site gives you a profile page where you can put not only some information about you but your backlinks as well.
27) Rebelmouse.com (DA 75) One of the top content curation websites out there, think of Rebelmouse like a Pinterest. Whats better, is you add all of your websites, and now when you power up Rebelmouse with links, you are also passing the juice to your other sites as well.
28) Aboutus.org (DA 72) A neat little website that lets you create a custom profile, setting up one is not that bad, you can use some HTML coding skills to format the content, but once you get it set up, you can not only add your main site, pop in some other links as well.
29) Authorstream.com (DA 72) You can think of Authorstream like Slideshare, its a website where you can upload presentations, like powerpoint or keynote. When you get your account set up, pop in your link, and its good enough to link to an inner page of your site too.
30) Pearltrees.com (DA 71) Another popular content curation website, this one is almost as powerful as Rebelmouse, so make sure you do the same, and add all of your social profiles and power up this bad boy to get the link juice flowing to all of your properties as well.