This is post is now quite old and the the information it contains may be out of date or innacurate.
Here are some handy shortcuts that you can use with Eclipse
Open any file quickly without browsing for it in the Package Explorer: Ctrl + Shift + R
Open a type (e.g.: a class, an interface) without clicking through interminable list of packages: Ctrl + Shift + T
Go directly to a member (method, variable) of a huge class file, especially when a lot of methods are named similarly: Ctrl + O
Go to line number N in the source file: Ctrl + L, enter line number
Go to the last edit location: Ctrl + Q