Retro Thing has published a short obit called
RIP: Hans Camenzind, Inventor Of The 555 Timer. The 555 timer IC (along with the 556 dual-circuit and 558 quad-circuit packages) has been widely used in inexpensive electronics since it was introduced in 1972 by Signetics.

MAKE has an article on the widely-useful timer by Charles Platt, who points out an interview at the Semiconductor Museum. Things were different in Silicon Valley back then:

There are no patents on the 555. Signetics did not want to apply for a patent. You see, the situation with patents in Silicon Valley in 1970 was entirely different than it is now. Everybody was stealing from everybody else. I designed the 555 Signetics produced it, and six months, or before a year later, National had it, Fairchild had it, and nobody paid any attention to patents. The people at Signetics told me they didn’t want to apply for a patent, because what would happen if they tried to enforce that patent, is the people from Fairchild would come back with a Manhattan-sized telephone book and say “These are our patents, now let’s see what you’re violating”.

Before the 555, many designers had to choose custom-made crystals as a basis for circuit timing. The crystals – which were often “overkill” as the circuits didn’t require that kind of accuracy –  were expensive and could take a long time to find and acquire. The 555 is also very versatile, capable of playing roles in many different kinds of circuits, like: pulse detection, bouncefree switching, touch switching, frequency division, capacitance measuring, pulse-width modulation, lamp flashing, pulse generation, logic clocking, tone generation, etc.

Many millions of 555s are still made each year. Many simple circuits using the 555 can be found on the web. For one example look at these at
This short video demos a sound generator (with more 555 videos in the sidebar).

Kamenzind’s book Designing Analog Chips can be found online in PDF form here.