Resistors is a program to calculate the most suitable E-series resistors for voltage dividers or for generating other values by putting two resistors in parallel. It is especially useful for selecting resistor values for the voltage dividers used in variable voltage regulators. In effect, the voltage in the middle of the divider is known, and you want to achieve a regulated voltage (the top value).
Taverna is a collection of workflow enactment and description components, including a high level language for workflows called Scufl (Simple Conceptual Unified Flow Language), a pure Java object model, parser to populate the model, and a set of views and controllers (including some Swing components to drop into your workflow-enabled applications). In order to actually run workflows you also need the myGrid workflow enactment engine.
DiaCanvas is a generalized version of the drawing canvas used by DIA. It extends some features used by DIA and adds new ones, while preserving as many of the original features as possible. This project is no longer actively maintained. It is suggested that you try DiaCanvas2 instead.