Ask HN: How do you integrate SaaS applications used by your company?

In your company you are using multiple SaaS/Cloud application (most companies probably do). Say online CRM (Salesforce, Highrise), help desk (Zendesk), e-mail automation, collaboration and document sharing (Google Doc, Dropbox), user feedback services (Wufoo), etc. How would you integrate them? Would you rely on SaaS provider to give you some basic integration? Would you write a code against the SaaS provider APIs and run it to some PaaS/IaaS? Would you use a Integration as a Service product like Snaplogic? What are the pros and cons in it for you?