Ashley Rich over at Delicious Brains relates some lessons learned from building WP Scanner, a WordPress-centric web app. The app was built on Laravel with Spark, and there's a WordPress plugin that is installed that communicates with WP Scanner's servers. Ashley mentions some of the third-party services he used. His advice about optimizing too early is worth noting:
I provisioned a server that was massively overpowered, which doubled my monthly running costs. This is something you just can’t afford to do in the early days when your product is making little or no money.