Ask HN: What processes and tools do you use to design software products?

I'm curious to know what processes and tools you follow to design software products?

At our organization things tend to start off with a Google Doc where we spec out descriptions for all the features of the product. Then we describe the various views, and couple them with mockups (either Balsamiq or Photoshop) and explanations of the data you push/pull on each view. We pull everything together into 1 document and refer to it as the master design document.

Are there any other tools you use in your product design process? Any templates you follow?