Today I'll write about a very recent new addition: 
slime-edit-uses bound to the keys 
M-? and 
M-_.
It is the logical counterpart to 
slime-edit-definition (
M-.) .
Basically, it's nothing more than a wrapper around the already existing Xref commands (
slime-who-calls, etc.) but it's a pleasure to use because a) it's just one key binding which does all instead of a multitude of different special-purpose bindings, and b) it's an easy binding (
M-? vs. 
C-c C-w KEY) and obvious as well (right next to M-. its counterpart.)
What does it do? Well see for yourself:
- on functions, it'll show a list of all call sites.
 

- on macros, it'll show a list of the sites the macro is expanded.
 

- on special variables, it'll list all the places the variable is set, bound, or referenced.
 

- on classes, it'll show a list of methods that specialize on that class. (no screenshot)
 
Of course, the usual disclaimer applies: The quality of this feature highly depends on how much Xref information your implementation is able to store.
Now, for me this begets the following question: How easy would it be to make SBCL collect Xref data during the build of itself?