The great age of language design, already waning in the 80’s declined in the 1990s. Okay, so I mean Java appeared in 1995, a creation of Sun Microsystems (now Oracle), and has been successful. BUT, at the time the thinking was it would be able to displace many of the ingrained languages, in their specific domains. This never really happened. Many universities took to teaching Java, but by the early 2000s, this trend had already started to reverse.
The greatest contribution of the 90’s was likely Python. Python, developed by Guido van Rossum, first appeared in 1991. Although not a “compiled” language, it was easy to learn, and extend.
Towards the end of the decade, the C standard moved to C99, incorporating some new data types such as long long, and complex, variable length arrays, and single-line comments in the form of // adopted from C++. Fortran too evolved, with substantial modifications, first to F90, then to F95. Fortran 90 was quite a radical revision for Fortran, one of the most interesting of which may have been the transition from fixed to free-style formatting. F90 also introduced modules, user-defined datatypes, array operations and features (sub-arrays, slicing), pointers, and of course recursion. F95 was in comparison, a minor revision. However the changes made in the 1990’s allowed Fortran to remain relevant as a programming language.