I'm not knowledgeable like the veterans, but I've seen lots of stuff done with the 555 and 556.
CrossRoads:
When I was a young engineer (in the mid 80's) we used to have bookshelves full of things like this from TI, National Semiconductor, Intel, IDT, Motorola, AMD, Atmel, etc.
Someday, maybe I'll post pics and tell the longer story, but on Independence Day, at a group picnic, a couple ladies showed up with boxes of books, and I acquired the lion's share of the stuff on electronics. No space available to sort through it all, but one day, maybe I'll get to it somehow and post a photo. Gobs of app. manuals, etc., from RCA, Sylvania, Fairchild (I think), on and on. Plus tube guides, HAM, RC, ... too much to list really.