Ask HN: How do you find what sites/services can help your business?

I see all these new y combinator companies/things people post on hacker news that would greatly help with various projects. For example, maybe I would like to use Stripe for my payments or Amazon S3 for storing data. But then there are less known companies like RankScience (randomly googled) that can help with your product. Is there a site that can help you find these more nuanced services?

I often read through new y combinator companies and think - oh I could use that, that would be useful. But I'm sure there are plenty of more established services that I just don't know about and wouldn't think to google but are super useful.