Dennis Ritchie never was a household name and probably never will be. However, he was the inventor of the language C, and one of the key inventors of the operating system Unix. These two inventions are integral to the world as we know it today and completely invisible. In all likelihood you have a derivative of Unix (or Unix-like system) embedded inside your broadband router, inside your PVR, and even inside your TV. Almost every major website you access today sits on the foundation of Unix, it underpins the infrastructure of the internet at every level, it carries your emails, it carries your facebook messages, your tweets and so on.
The vast majority of every other computer based system you use, and by that I mean anything that contains a microcontroller upwards was in all likelihood coded in C, built using systems that use C, or designed on systems written in C. That scripting language you're using probably uses a C based runtime. That browser ? C based. That iPhone with the objective C based apps, or C++ based apps - again C derivatives.
What about non-programmable things? Like watches, or similar ? Well, lots of those are pure hardware only. No Unix, no C. Clearly no influence ? Well, no actually, lots of influence. One of the major languages used in the design (and implementation) of hardware is a language called Verilog. What was one of the (creditted) design goals of Verilog? "The designers of Verilog wanted a language with syntax similar to the C programming language, which was already widely used in engineering software development.". Yep, because C was so successful, useful and portable, they wanted a version of it that worked well for designing hardware. OK, the resulting language does look very different, but that doesn't mean that the inspiration wasn't there.
So, one way or another if you're using something electrical that's even vaguely "intelligent", it's been touched by the influence Dennis Ritchie, directly or indirectly. We're richer for him having been with us, and poorer without him.