A brief look at some of the different kinds of computer languages: Computer Language Paradigms.
Dictionary of Programming Languages has descriptions of 145 languages.
99 bottles of beer is an excellent web-site, with examples of hundreds of computer languages, created by Tim Robinson. (It used to be at http://www.ionet.net/~timtroyr. He was rebuilding his site at http://members.home.net/tim-robinson/ but that seems to have gone as well. It seems to have been replaced by a site that used to be a mirror, with 904 languages last time I looked.)
Other sites with lots of example programs in different languages:
Syntax across languages - a comparison of the syntax used for various concepts across several different languages.
Lots of links about computer languages from Open Directory Project (DMOZ). This classifier has nearly every link about computer languages that you might ever need, including lists of 2189 and 2350 languages (via "Directories") but not: The Esoteric Programming Languages Ring
ISO standards for Languages used in information technology (not sorted by language, and contains language bindings for various packages, but seems to include around 20 languages) and ISO working groups for Programming languages, their environments and system software interfaces (lists about 10 apparently active groups)
Wiki Pedia on Programming Languages
Which languages are actually in use?
Some jokes and stories about programming languages:
Other introductions to Programming Language Paradigms etc.: