The hack
Get your product seen and build backlinks by getting listed in directories.
Why it works
Getting listed won’t make or break your business, but it can get you eyeballs for free. When you’re short on money, but have time, this can be a good investment. The best side-effect is that you’ll get backlinks whether or not you’ll get users from it.
How to do it
There is this amazing free sheet by Roman Vasilenko, that lists over 280 directories. Go over it and see which are the most relevant for you. Also, read his post on how he made the selection.
There is also this free list made by folks at Learning loop. It’s a little less structured but has over 350 places you can list or post.