People always assume that they only way to promote is to build a website and rank it. You can always build content on someone else's site and rank it. Lots of people build review sites on Squidoo. However, you can always build up a forum thread, article, video, yahoo answers page, ezine article (although if direct linking to an offer... you must first build a site to link to and then redirect after publishing to your affilliate offer), etc.
They can be SEO'd or sent paid traffic like any other site. In fact, if you know how to provide value in an answer and disguise your sales agenda well, people eat these up even more. The most powerful sales message is the one where people don't know they're being sold to.
You also sell stuff on forums like ebooks etc.
Of course, one really simple forgotten way is to write a quality piece of content. Then send it out to somebody in your mailing list to use as content and have the forward to your offer. Some people will take your free article and disappear but many will use it and provide you with affiliate commissions to their list for splitting a part with them.
Of course, selling backlinks works every time all the time no exceptions. I have a site where I actually resell 10 fiverr gigs as a package. I found the best 10 backlink packages I could find (for $50 naturally) and resell them for $100. I do have a website for that but I even use people on fiverr to promote is for me. LOL.