Molybdenum is an IDE for creating, editing, running and recording testscripts for Selenium, a browser integrated testtool from http://thoughtworks.com.
Molybdenum is build as a Mozilla Firefox extension/application.
Abbot for SWT is a Java framework that lets you more easily write JUnit tests that target Eclipse-based SWT/JFace UI. It also supports the Eclipse GEF & GMF graphical editing frameworks and has some support for WTP (web tools project) UI.