Ask HN: What Paid Services/Softwares Do You Use For Your Startup at the moment?

For your startup, what services do you use? I'm using Google Cloud storage for static assets hosting, Olark , FreshBook, Twilio , OpenVPN with private tunnel, Skype subscription, Google Voice, Sendgrid, Godaddy, Dreamhost, Prey (Preyproject), WISO Steuer (German Taxes), Hellofax ( planned)...and a couple of others.

What paid services or softwares do you find the most useful and critical in running your startup ?