• Highly customizable "quick and dirty" utilities for doing everyday things. (i.e. as the most powerful scripting language available).
• Large, complicated, mission critical applications which would be impossible to develop in any other language.
• Fast prototyping and Rapid Application Development (RAD).
• Continuous-availability applications, especially those that require functionality changes after initial deployment.

It is sometimes used to define every aspect of an application, sometimes just the internal processing engine (i.e. the guts, without the User Inteface), or sometimes just the user interface. Sometimes it is used as the "glue" to interactively develop Graphical User Interfaces and sometimes to define graphics/windowing systems themselves.

It is often used to provide interactive command languages, macro or scripting languages, and extension languages embedded within commercial systems.

It is widely used to programatically generate other, static, stand-alone applications, in the same or different language. It is also used to generate "mobile code".

This site lists a sampling of commercial uses, listed by industry, and reasearch uses.

This site also gives a description of Lisp and its features, available tools written in Lisp, and a comparison with other languages.