The Bourne shell was first released in 1977 (37 years ago).
The C Programming Language book was published in 1978 (36 years ago), describing the C language which had been out for a few years.
Python was first released in 1991 (23 years ago). The first version that looks very much like the current Python was version 2.2, released in 2001 (13 years ago), but the code from Python 1.0.1 is already pretty familiar to my eyes.
The future might point in the direction of functional languages such as Haskell, which first appeared in 1990 (24 years ago), although the first modern version is from 1998 (Haskell 98).
The web was first implemented in 1989 with some preliminary work in the early 1980s (although the idea of hypertext had been around for longer).
The only really new software I use regularly is distributed version control systems, which are less than 20 years old in both implementation and ideas.
Edit: the original version of the post had a silly arithmetic error pointed out in the comments. Thanks