The easiest way I can think of would be to install the Force.com IDE, create a new project that includes all SObjects in the org, and then use a tool like Windows Grep to search through the generated
objects directory for certain strings depending on what you're interested in.
<masterLabel>Test Execute JS</masterLabel>
So your best bet there would probably be to search for
You'll need to play around with it and look through the object metadata files yourself to determine the best way to group your searches. For example, if you were interested in links as opposed to buttons, you would look for
Note that this method will not return results for buttons in Visualforce pages/components. You would need to search through the respective directories in your Force.com IDE project for those.