Turnkey visualization applications offer a fixed functionality to solve a limited range of specific problems. The user supplies the data and the computational instructions to the main program and possibly some geometric mapping. The application supplies the main program and rendering and usually has a nice user interface.
Many turnkey visualization applications are extremely application-specific and of limited use in other fields. They are often available on few hardware platforms. However, they have the advantage that these packages do not require programming. Thus, one can obtain results quickly. The disadvantage is that they are inflexible and have only limited extensibility. Therefore, they may often provide only part of the solution that the user requires. They have all reached a high level of maturity and many users applying visualization to their work will probably use one of these packages.
An example turnkey application (PV-Wave) from Visual Numerics. This application is actually quite general and not problem specific.