If you need validation, the quick way is to setup some adverts. Google, Facebook, Twitter, etc. Or find a place where you can spread your pitch and link. You should have some kind of validation goal, like email signup or trial download or something.<p>Product Hunt is a good place or maybe some beta sites like BetaList to get started.<p>The longer and "cheaper" way is to write your own content, which gets attention. It depends on how connected you are already. Some people have already a huge interested audience.
Self-promotion. If I had such a project I'd be adding a little link to it here, and talking about how awesome it was..<p>But you need to either build an audience, pay for adverts and be optimistic, or be constantly promoting it in all appropriate venues. Having google-alerts, and twitter-searches, to make sure you can join suitable threads promptly is very useful too.
Before launching a product, I followed the advice to build up an audience first. For instance, having a website, that is somehow in the context of the product, and write about the topic constantly. Afterward you can redirect the audience to your product.