What’s a guerrilla marketing strategy you’ve seen used recently to great success? Be specific.

The following answers are provided by the Young Entrepreneur Council (YEC), an invite-only nonprofit organization comprised of the world’s most promising young entrepreneurs. In partnership with Citi, the YEC recently launched #StartupLab, a free virtual mentorship program that helps millions of entrepreneurs start and grow businesses via live video chats, an expert content library and email lessons.
1. Surprise Deliveries

My good friend targets local SMBs with his product. Instead of calling them non-stop like everyone else, he decided to hand-deliver them a package. He put on his courier hat and delivered boxes with a bow tie that had a special invitation to learn more about his product. Surprisingly, the campaign worked — he received almost 100 leads using this method that turned into paying clients.
Jay Wu, Best Drug Rehabilitation

2. Meme of the Day

From “Binders Full of Women” images to “Gagnam Style” music videos, whatever the hot trending topic of the day is, you can leverage it to your brands advantage so long as you can act quickly. If it’s buying a domain name and directing it to your website or producing a funny image based on a current affair in the 24 hour news cycle, act fast and creatively to get your brand extra exposure.
Benjamin Leis, Sweat EquiTees

3. Shout It Out!

In the Netherlands Domino’s Pizza modified their delivery scooters to shout the Domino’s brand name whenever the driver would shift gears. This guerrilla marketing campaign resulted in a very funny bit for the people on the streets and received a ton of local press.
Anthony Saladino, Kitchen Cabinet Kings

4. Fake Cease and Desist Letters

I know of a company that’s about to send fictitious cease and desist letters to a hundred of its potential customers. The letters ask those customers to stop making less money and growing too slowly by ignoring the potential that working together presents. The aim is for the letters to appear very real, and thus create moments of fear and confusion, before an “ah ha” branded realization.
Derek Shanahan, Foodtree

5. Top 10 Lists

In every industry there’s the opportunity to create dozens of different top 10 lists that you can post on your blog, distribute to media, etc. The best part is that by placing others on your top 10 list, you can leverage their media contacts as it’s almost guaranteed that they’ll want to share and promote your list that they appear on.
Derek Johnson, Tatango

6. Email Signatures

My favorite recent marketing hack that I’ve seen is people sharing whatever piece of news or article they most want to promote within their default email signature. If you’re sending emails to 100+ people a day, imagine what percentage of them will click on it!
Derek Flanzraich, Greatist

7. iPhone / Android Backgrounds

For my latest startup in the health and wellness space, we’ve seen great success by offering our visitors mobile phone backgrounds with positive affirmations (http://elitehealthblends.com/category/affirmations/). These affirmations keep our brand in front of the user and keep them motivated to reach their weight loss goals. So far the users are loving it and having great results.
Nick Reese, Elite Health Blends

8. Creative Collateral

I recently noticed a person was trying to promote his used guitar sales business. Rather than creating a traditional business card, he used an actual guitar pick. It had the name of his business on one side and the phone number on the other. His business picked up significantly after he started distributing those.
Andrew Schrage, Money Crashers Personal Finance

9. Viral Video

When we opened Noodlecat (http://noodlecat.com/), my wife started a viral Web campaign with the cat in different places around the world. The final piece was a video that announced Noodlecat had finally landed in Cleveland. You can check out the video on our website.
Jonathon SawyerSeeSaw Restaurant Group

10. Inserts in Books

This is one of my favorite guerilla marketing strategies and I’ve seen it done a few times. Business owners put a well-designed postcard in the center-fold of books within their niche. One clever one was a call to action for a free download that was relevant to the book’s content. I’m sure Barnes & Noble would be less than thrilled but I thought it was clever.
Natalie MacNeil, She Takes on the World

11. Do Good, Guerrilla-Style

We’ve brought guerrilla marketing to energy efficiency. The greeNEWit Founders also own the Baltimore franchise that is part of the international chain AArrow Advertising. Since early 2010 we’ve been using greeNEWit as an effort to employ some of the inner-city kids we work closely with in Baltimore and rely on the AArrow Sign Spinners to increase awareness about the initiatives at greeNEWit.
Jason Jannati, greeNEWit

12. Flashmobs Are Still Amazing

Flashmobs grab people’s immediate attention. But with proper filming and story-telling, they have the opportunity to go viral, spreading the messages well beyond the folks who witness the event the first time. T-Mobile created a flashmob in a train station that as of October 2012 has over 36 million views. The people “in attendance” have a great story, but the rest of the world still can enjoy too.
Aaron Schwartz, Modify Watches

13. Company T-Shirts

We design, print and distribute creative company t-shirts that our team actually wants to wear. Internally, it builds company pride, while externally each employee advertises for the company in every public space they enter. This helps with both sales and recruiting efforts.
Robert J. Moore, RJMetrics