These are the languages I know something about. My experience ranges from a couple of
days playing with them to more than 15 years of professional use.
My interest in programming languages originates from an embedded project which also
included a FORTH "compiler" implementation - from scratch.
Formal Specification Languages
ITU languages
SDL
Specification and Description Language
SITE
SDL Integrated Tool Environment
(Humboldt-Universität zu Berlin)
MSC
Message Sequence Charts
the Z notation
LTL - Linear Time Logic (online book)
CTL
- Computation Tree Logic (online book)
ASN - Abstract Syntax Notation
Modeling
Promela - modeling language of the SPIN formal verification system
UML Unified Modelling Language
(Object Management Group)
SCXML State Chart XML
Graphical
G - LabView's graphical language (National Instruments)
Markup
HTML HyperText Markup Language
CSS 2 Cascading Style Sheets
XML EXtensible Markup Language
XSL Extensible Stylesheet Language
XSLT XSL Transformations
Line-oriented XML
docbook the Official Documentation Format of Linux
OpenDocument - open file format for office documents:
text, spreadsheets ...
SVG Scalable Vector Graphics
MathML Mathematical Markup Language
Scripting
bash Official Shell of Linux
PHP Personal Home Page
Tcl/Tk Tool Command Language/Tool Kit
Expect
Perl the Swiss Army chainsaw of scripting languages
Awk from Aho, Weinberger and Kernighan
sed - stream editor
JavaScript
Relational
SQL Structured Query Language
Logic Programming
Functional - Haskell, SML, Caml ...
Equational
Object Oriented
Procedural
HDL - Hardware Design Languages
Compiler Construction
Test Language
TTCN 3
Testing & Test Control Notation
Lambda the Ultimate The Programming Language Weblog