Ask HN: What are the big (or buzzworthy) softwares in Microsoft and .NET?

A couple of weeks ago I met with a potential client at work. We deal mostly with custom electronics, microcontrollers, embedded Linux, that soft of thing. I'm hired to do the embedded Linux thing, along with some higher level stuff, like setting up servers and all that.

During this meeting, the client wanted to aggregate information from lots of devices into one place. He mentioned some piece of software (I don't remember he name now), and I said I had never heard of it. The response I got was rather snazzy, he said something along the lines of "oh, it's only one of the biggest CMS systems in the world, nothing you should know about". Turns out, it's some .NET software, so it was not under my radar.

I'd rather prevent this from happening again, so I'm reaching out to you guys.

What are the major softwares from the Microsoft world I should at least know by name, so that I can sound smart when the next potential client comes around?