The MathExt library was made to parse and calculate formulas of any complexity. It can easily be integrated into web applications. As developer you can set all kind of settings. You can even specify what commands should be available to the user.
OpenJX is a Java XML form language similiar to Flex. In a few simple lines of XML and Javascript, a developer can create a fully featured Java application or applet. OpenJX also features a network based plugin system which is extremely powerful.