Stitch Data is our tool for integration: they get the data and push them into Redshift. They have a very nice free tier.
Mixpanel copied this tracking feature from Heap and released Autotrack.
We also use Heap Analytics--it is really really good for people starting out. They basically track everything that happens on your websites and generate the definition for the event retroactively. It is also pretty reasonably priced.
Google Analytics is a great tool, but it is really complicated to do things beyond the simple things. It’s very aggregated and you can’t look at specific users.
We like Slack a lot--it is good for team collaboration, has great integrations, you can create and destroy channels easily, communicate through different time zones, etc. They also keep adding new features like video call. They bought ScreenHero so you can also pair program. We use it for notifications and alerting--it greatly reduced email exchanges within the company.
We are using the Mandrill feature for transactional emails.
MailChimp is very cheap when you get started, but for us it is getting pricey. The template manager is great. It is responsive and has easy tools to do A/B testing. We are pretty happy with it. The user-facing side is quite great; the limits are on the developer side--if you want to do advanced integrations, it becomes really hard.
Right now we are using Braintee through Recurly. We switched to Recurly and then we just wanted to consolidate. We went through Braintree for PayPal support. It is decent. Our business team likes it because it has phone support.
Trello is nice. It is very confusing at first how to use it. You have to figure out your own flow which can be tricky but at least once you figure it out, it is easy to modify if you need to. You can connect to Slack, Google Drive etc. It is easy to communicate and make to-do lists.