Ask HN: best outsourced QA testing service / practice?

Had an frustrating experience with a vendor's web site and would like to point them toward outsourced load-testing and QA testing services.

Seems to me there should be a service that lets you create test scripts to run against your website, then run them in numerous available browser platforms, then run n simultaneous requests with those scripts as a load test, and report back.

Like LoadRunner as a service for web sites.

Anything like that exist? Or what's best practice to avoid giving cranky clients like me aneurysms with a non-functional web site?