Below are some of the places I have found or been referred to that can you give you a decently good link without content or involving minimal work. Try them out for yourself and you'll be surprised how much link juice (and sometimes targeted traffic) they can pass on!
1) HARO (Help-A-Reporter-Out): Okay, so I never said any of these sources were top secret insider tips or anything, so don't flame me for giving out some useful (if not exactly unique) advice. Helpareporterout.com sends you unique alerts every day to become a source or citation for news articles published on the web and other media. It can be expensive ($150/month for the top package) but the quality of exposure can be immense. You can have links published in newsletters for college publications (there's a valuable .edu link btw) and various small news outlets around North America.
*Points to mention: Sometimes the value of the link in these cases might not be great from a PageRank or Domain Authority perspective, however, there can be a decent amount of targeted traffic harvested from these links for very little work. Oh, and it's not just country bumpkin newspapers using HARO either. Inc.com, Fox News, Better Homes and Gardens, and NBC have all used HARO in the past. If you're in a big niche like weight loss/nutrition/technology/finance/health & fitness then I would definitely recommend subscribing for at least a month to try it out. With their $50/month package you will get at least 90 link opportunities per month sent to your inbox.
2) .edu Newsletters & Student Publications: Specific student groups are always looking for guest speakers on relevant topics and will often add this announcement to an online student publication, check with local city colleges and Universities to find out if you can be one of their speakers. This can result in a powerful .edu link back to your site, and position you as more of an authority in your niche. Most colleges have pages like this where you can browse student organizations. Depending on the popularity of the student group, you might even get a promotional mention on the news section of the homepage to the college
3) Gifting to Industry Leaders: Who doesn't like a good gift? Sending out presents and cool stuff to bloggers and thought leaders in your niche is a cool way to start building a relationship with a powerful authority (a guest post might be in your future!) but it can also get you a mention in their blog (in my experience, bloggers love to talk about this kind of stuff since they always need content to stay fresh) and will very likely give you a callout on their Twitter/Facebook. How can you do this?
Just ask! Fire a quick email over to the person in question and say that you have enjoyed their blog over the past year and learned a lot and want to thank them by sending them a little thank you in the mail. Not all will respond and say yes, but it's a numbers game. Ask the 100 top bloggers in your niche and maybe 25 will say yes.
What should you send? Something small, useable, and related to your niche if possible.
4) Charity: Make a charitable donation to an organization (niche related would give the most value) to get a link on their donor page. Need to find these organizations? Try a few of the following search queries in Google:
[niche] "donate to us"
Some of these searches will return opportunities to guest post too, so there's something else to keep in your pocket down the road
5) Broken Link Building: Brian Dean is a link building pimp. I'm not going to bother explaining why this method kicks ass, but you should read his and Neil Patel's blog post about how to do this effectively right here: Black Belt Broken Link Building - The Advanced Guide to Link Building
Oh, and if you think this entire 9-part post is beautiful, keep in mind that Neil dropped $50,000 to get it made...
6) Fundraising: No, not like KickStartr. I mean fundraising for worthy causes. Matthew Barby has a great suggestion to head over to JustGiving.com and start a project to raise money for a worthy cause. You can run a marathon to raise money, or just post a project and ask for donations. In any case, all the links are dofollow and they can gain significant PageRank if you reach out to the right people to raise awareness. Check out this PR2 page with a nice dofollow link all for raising money through a triathalon
7) Scholarships: Setting up a scholarship in a field related to your niche is also a great idea. It will be costly, but the advantages of getting listed on various .edu pages will certainly provide much link juice. It doesn't have to be tens of thousands of dollars either, some local scholarships are often just contributions of $500-$1,000.
Not all of these strategies are for everybody, maybe you have something you prefer? Post it below and as new strategies get added and validated by other Warriors I will add them to the list
Remember, it should require little-to-no new content or have minimal work involved.