I really enjoy posts like this. I've long had an idea to start a site like usesthis.com (The Setup) but to interview startups and ask them what tools and services they use internally.
At Crunchbase we were going to expand company profiles to include services and tools. We started with PR agencies and law firms[1], etc. as service providers, but we never found a chance to expand it to more general tools and services.
Does anybody know if a site like that already exists, or is anybody interested in implementing something like it?
[1] eg. look at http://www.crunchbase.com/company/facebook - down the left-hand side menu you'll find a section called 'Service Providers'