Grep'ing within my current project is something I do frequently. It's not much to type, but I do it often enough that I was looking for a keystroke. Most of my projects are Clojure and use Leiningen, thus I'm able to make some pretty safe assumptions. The following snippets allow you to easily grep within your project.
note: both use expand-region to grab the clojure that the cursor is on or immediately after, and grep for whatever was selected.
grep recursively starting at the directory where the project.clj file lives
grep recursively, but allow the user to select the root directory (defaulting to the location of the project.clj file). I often use this one for selecting only the src or test directories of my project.