As already mentioned, tern.js is a new and promising project with plugins for Sublime Text, Vim and Emacs. I´ve been using TernJS for Sublime for a while and the suggestions I get are way better than the standard ones:
Tern scans all .js files in your project. You can get support for DOM, nodejs, jQuery, and more by adding "libs" in your .sublime-project file:
"ternjs": {
"exclude": ["wordpress/**", "node_modules/**"],
"libs": ["browser", "jquery"],
"plugins": {
"requirejs": {
"baseURL": "./js"
}
}
}