Wow. Looks like you have outsourced every imaginable job when there's a webservice for it.
Are you doing this because of bad experiences when servicing your own or did you do this from the start? Did you compare the running costs/reliability between outsourcing and self administration with a positive result into outsourcing?
Interesting. I think most of this stuff is not a core competency for a startup.
I guess my responses are:
1. Zendesk
We needed a good system, not really outsourcing of support. So, we do our support in-house but we use the Zendesk SaaS system to manage it.
2. GetSatisfaction
As above.
3. SendGrid
Email deliverability was not a piece of expertise we had in-house, especially when we were 2-3 people. Now we're 10-ish, our sysadmin guys STILL don't want to do this stuff.
4. MailChimp
Hand-coding HTML emails more than once was boring.
5. Apigee
This is something we were on the fence about. The metrics visualization probably swung it.
6. String
No-brainer :)
7. ExpressionEngine
Still a bit of friction in the decision between self-coding or using EE. But it's the 'annoying' stuff that swings it like plugin availability for new functionality, rather than do-it-yourself.
8. Chartbeat
Couldn't do this ourselves.
9. Mint
Could do this ourselves, too cheap to bother.
10. PivotalTracker
As above.
11. Salesforce
Industry standard, makes sense to outsiders, reliable.
12. RightSignature
Awesome. No point building ourselves. Legal worries too if we did.
13. Gotomeeting
Yeah no way we want to build this.
14. Xero
The non-enterprise stuff we do is billed through our own app. But Xero makes sense for invoicing and proper accounts. Risk is, if you build it yourself, you need to know GAAP inside-and-out AND still it's a concern for outside auditors I think.
15. Dropbox
Yeah no way.
BONUS: Office Glico
Well, we could get an intern to go to the mom&pop store every week. But no.