Flex Builder 2.0 has some really great ways to quickly navigate through your source code – e.g. “go to definition” and stuff like that. Most of these are based on similar features in Eclipse’s Java editing environment (the JDT).
Ctrl-O: Lightweight popup with list of functions in current file. Great for quick navigation within a file.
Ctrl-Shift-T: Open type. A quick way to go to the source for any class.
Ctrl-Click or F3: Go to definition. Ctrl-click on just about anything – function name, variable name, etc. – to go to its definition. F3 does the same thing.
Alt-Left, Alt-Right; or yellow arrows on toolbar: Back, Forward navigation, like in a web browser.
Ctrl-Shift-O: Organize imports – makes them alphabetical and tidy.
Ctrl-Space: Code hinting (of course).
Ctrl-Shift-Space: Restores tooltip showing the args of the function you are trying to call, e.g. if you have already written “foo(” but then moved somewhere else so the codehint had gone away