I believe the problem with "go to" packages is that they would work diferently for each language.
If you use Javascript js-hyperclick and hyperclick (since code-links is deprecated) may do what you need.
Use symbols-view
package which let your search and jump to functions declaration but just of current opened file. Unfortunately, I don't know of any other language's equivalent.
There is also another package which could be useful for go-to in Python: python-tools
As of May 2016, recent version of Atom now support "Go-To" natively. At the GitHub repo for this module you get a list of the following keys:
symbols-view:toggle-file-symbols
to Show all symbols in current filesymbols-view:toggle-project-symbols
to Show all symbols in the projectsymbols-view:go-to-declaration
to Jump to the symbol under the cursor symbols-view:return-from-declaration
to Return from the jumpI now only have one thing missing with Atom for this: mouse click bindings. There's an open issue on Github if anyone want to follow that feature.