Springloops - Deployment
Pivotal Tracker - Agile planning tool
Podio - Get work done
New Relic - Server/Application performance monitoring
Pingdom - Uptime monitoring
Blame Stella - Speed monitoring
Sendgrid - Email delivery
CloudFront - CDN
Free services:
Groove - Support tickets & chat (groovehq.com)
Trello - Organization
Stripe - Payments
Other "stuff" I pay for that's not quite SaaS: Linode, Twilio, ThemeForest.
Skype - phone calls
Pivotal Tracker - Agile - Yo baby!
Raven Tools - SEO and reporting
Freshbooks - Billing
Quickbooks online - "accounting"
Balsamiq Online - Collaborative Mockups
and I think my new SaaS that I will be announcing in about 5 days will be well worth the money :-)
Github
Pivotal Tracker
Airbrake- Error Reporting
S3 if it counts
Helpjuice, for the knowledge base, of course
Github
Skype
Dropbox
Olark
VisualWebsiteOptimizer
Stripe - payments
Sendgrid
Linode (switched from Rackspace)
Balsamiq
hipchat
xero
skype
dropbox
isocket
shopify
rysync.net
Salesforce
Amazon Web Services
Dropbox
Bill.com
Jobvite
Github
Pingdom
Cloudkick
Passpack
Meraki
MS Intune
Unfuddle
Evernote
Skype
Skitch (before it joined Evernote)
S3 & Linode (but that's hosting)
dropbox
sendgrid
skype
(app engine)