We are often asked about what software, tools and services we use on a daily basis. Here's just a gist of it. The list starts from simple tasks like sending and receiving email and goes deep down to the technologies that power our software and services development.
Google Apps is what powers our business management. Emails grouped into conversations, instant messaging with video conferencing, collaboration on any kind of document or drawing in real time are just a couple of invaluable and unique technologies offered by this service today. Not to mention, all of its features are available on mobile devices!

We use Google Drive for all office tasks, including financial reports generation. Of course, Apps Script is a huge addition to this, which allows us to automate many operations. 

Not only this unique product makes it much easier to collaborate, it also saves us a lot of money on otherwise not so productive and/or often expensive alternatives every day.
Aside from being the safest and the fastest browser, Google Chrome provides a great set of tools for application development.

We use all mainstream browsers during our testing but when it comes to debugging and optimizing a website or an application, Chrome Development Tools really shine among others.
BigQuery is a priceless tool for all sorts of ad-hoc queries, statistics analysis and data generation for a dashboard. It sets the bar very high by querying 1TB (Terabyte) of data in 24 seconds!

BigQuery comes with a very handy command line tool bq and a slick web UI. Not only that, the queries can be launched from within an Apps Script!
Many of our internal web tools and public sites are running on Google App Engine. Aside from its simplest deployment process ever and invaluable core components like auto-scale scheduler and Task Queues, it also has a number of handy APIs which allow us to concentrate on the application development and its features instead of wasting time on configuring the underlying systems and loosing the focus otherwise.

Additional tools such as AppStats and Testbed make it even easier to debug, test and measure performance of an application.
We have some legacy code that unfortunately cannot be run on Google App Engine. Fortunately, there's AppFog! It is another Platform As A Service (PaaS) provider, based on CloudFoundry technology.

A notable feature of AppFog is that they have partnered with quite a few Infrastructure Providers. This allows one to deploy an application in different regions and continents based on specific needs.
When neither App Engine nor AppFog suit our needs, Rackspace Cloud Servers is there to rescue! Built on the OpenStack technology now, it is very easy to manage virtual servers. One of the features we like is being able to create image snapshots without restarting a server instance. This allows us to do seamless upgrades and maintenance.

It is also worth mentioning their very competitive pricing and Fanatical Support!
While Google Drive is good at assets sharing and collaboration, Cloud Storage is great when it comes to resources management within a website or an application. It has proven to be very fast and highly reliable.

In addition to have rich and simple API, the product also provides a handy command line tool called gsutil which we integrated with our deployment tasks and processes.
Closure Tools is what allows us to write high profile JavaScript apps. Closure Compiler is the best at optimizing JavaScript. Not surprisingly, Closure Library is a huge amount of useful and well-tested
code - most famous Google products were written using this library! One of the many notable library's features is ModuleManager.

We also use Closure Templates to generate HTML on the client side.
We love Go! Not only because of the cutest logo. Being statically typed language that is capable of compiling an (web) application down to the binary, an executable file, Go allows us to create very fast and efficient apps with a tiny memory footprint. Being a supported runtime on App Engine, it's a great combination!

Go also shines at modularity, built-in support for testing and code formatting, but most of all, at its core ideas. We're happy to see it being adopted by so many organizations
No less than Go, we love Python! Mature, backed by a very good documentation and nice community, Python is used in almost every our deployment script. There's one way to do something in Python, and it works exactly as advertised. No magic.

We use Python for writing web applications too. An impressive amount of great libraries exists today, which makes app development fast, easy and fun.
Code review is at the core processes of every our application development. GitHub's "pull requests" are nice but we like Rietveld because it can visualize side-by-side diffs. We normally use hosted version.
Bitbucket from Atlassian is what we use for private code hosting. With the recent facelift it got even better!

Opensource projects go to Google Project Hosting and mirrored at GitHub. Our preferred code versioning systems are Git and Mercurial.