Queries

source:/implementors/fooBar

Find all implementors of #fooBar and show a list of those methods.

source:/senders/fooBar

Find all senders of #fooBar and show a list of those methods.

source:/messages/Class/fooBar

Show a list of all messages that the method Class>>fooBar sends.

source:/vars/Class/varName

Find references to the variable varName, which is visible in the scope of class Class.

Other types should be added when the need arises. The source: accessing scheme should return reasonable output for partial paths, for example:
source:/vars/Class should show a text with a list of the variables visible from Class, probably excluding the global ones. Output could look somewhat like this: (Your browser will display an error message when you try to follow the links...)

Variables in Class (subclass of SuperClass)

Instance Variables

foo, bar

Superclass Instance Variables

baz

Class Variables

Mumble