I was doing software security semi-professionally before the 8lgm Sendmail 8.6.12 vulnerability that set off the modern buffer overflow craze, and worked with a bunch of people frantically reconstructing that exploit (which wasn't published) --- the authors of the first x86 stack overflow vulnerability included my future business partner at Matasano, Dave Goldsmith.
It was light night and day! Before overflows, there was a whole variety of different "kinds" of exploits (you got some command injection with metacharacters, for instance with SunRPC services calling popen and system, but you also got "overwrite a file" or "leak a file" or things like that). Afterwards, it was just: every machine on the Internet had remote code execution via overflows.
It used to be feasible to calibrate an stack exploit for a remote service, for which you didn't even have source, in an hour or two of tinkering. It's crazy to think of how far things have gone since then.