These things are possible in dynamic languages with static analysis, it's just not as easy. (Oh, and if you write code that's unreadable, then the static analysis fails. But most people don't do that.)
Personally, I have all the pieces together for doing this with Perl, but I have not put it together into anything coherent because it's largely useless. An occasionally-updated tags table is really all I need, so I can't get motivated to make "Eclipse for Perl".
Maybe someone else that sees the value in these tools will do it. Let me know what information you're interested in, and I will show you how to implement it.