Yesterday I finally got around to using 2 great tools that made browing large source code trees really easy, and of course well integrated with vim.
The first is called ctags — though it can be used for many other things, I primarily use it to list variables, functions, classes, macros — the kind of things Emacs’ speedbar does — of the file that I’m currently viewing. It works with a plethora of languages, and the Vim interface is pretty funky.
The other is called cscope — a tool much like ctags, except that its specialized for cross referencing C/C++ based source code. So given a function name, it can tell me where that function is defined or called at in the entire source base — this is particularly useful, for instance if you want to trace an execution path in the Linux kernel!
Long live open source!