Intercom (http://intercom.io) - CRM and user messaging

Chartbeat (http://chartbeat.com) - Realtime analytics

Sendgrid (http://sendgrid.com) - Sending email from an app

Dropbox (http://dropbox.com) - File sharing/storage

CouchDB (http://couchdb.apache.org) - Flexible database

Intercom looks pretty cool - is it intuitive for business users to use?

Yeah we love it for two reasons:

1. Our users can send messages to us from inside the app. They end us using this to communicate with us more than email.

2. The dashboard for site owners is awesome. It shows you overall user count, who is logged in right now, each user's social networks (pulled automatically using http://www.fullcontact.com), and gives you a whole bunch of ways to filter the information.

Trello (https://trello.com/) - task management

Statsd (https://npmjs.org/package/statsd) + Graphite (http://graphite.wikidot.com/) - monitoring & graphing

Kippt (http://kippt.com) - link and article saving/sharing

Zapier (https://zapier.com/) - like ifttt for business

Heroku's Hosted Postgres (http://postgres.heroku.com) - DB as a service

Also definitely agree with Intercom, Dropbox & New Relic, all great services.

We use a lot of services at DNSimple. Here are some of them:

Chargify (http://chargify.com/) - recurring billing

Stripe (http://stripe.com/) - payment processing

Librato (https://metrics.librato.com/) - metrics

Mailgun (http://mailgun.com/) - email service

Boundary (http://boundary.com/) - network analysis

Papertrail (http://papertrailapp.com/) - consolidated logging

PagerDuty (http://pagerduty.com/) - alerting

TravisCI Pro (http://travisci.com/) - continuous integration

CodeClimate (http://codeclimate.com) - static code analysis

BugSnag (https://bugsnag.com) - exception tracking

Also, other services that have already been mentioned (like Github, Intercom, Trello, Dropbox, Sendgrid, NewRelic, etc)

BrowserStack (http://www.browserstack.com/) - Test Websites on different os and browser setups, in your browser.

Recurly (http://recurly.com) — Recurring billing managment

Intercom (http://www.intercom.io) — User management/intelligence

Postmark (http://www.postmarkapp.com) — Transactional email

Trello (http://www.trello.com) — Productivity tool

Sentry (http://getsentry.com) - Exception tracking

Postmark (http://postmarkapp.com/) - Email service

Intercom (http://intercom.io/) - CRM

New Relic (http://newrelic.com) - Application monitoring

MongoLab (http://mongolab.com) - MongoDB-as-a-Service

I'm assuming it's already on the old list, but I haven't seen Github (http://github.com) listed -- for us, Github is the application we use.

I also haven't seen Mixpanel (http://mixpanel.com), but I see a lot of Intercom. Now that Mixpanel has "Engage" (which seems like an Intercom-like thing), is there a compelling reason to use Intercom alongside Mixpanel, or are they mostly overlap?

Another platform I see missing is dotcloud (http://dotcloud.com), which I don't use for everything, but definitely enjoy one-click, hot standby, fault tolerant (well, as tolerant as it can be) MySQL databases.

Last thing we use that I haven't seen listed is Amazon SES (email). I love the no-commitment pricing and paying for what we actually use instead of having to pay a minimum fee and all that.

Also shoutouts for Stripe and Trello.