Available meta data in Confluence and JIRA

Atlassian uses  something called AUI or Atlassian User Interface that is basically a set of reusable, cross-browser tested UI components (markup, CSS and Javascript) that are based on jQuery and jQueryUI. They are used in most of Atlassian products like JIRA an Confluence.
Common trick for saving some meta-data about the web app and the currently logged in user is used.

<meta name="ajs-context-path" content="/wiki">
<meta name="ajs-version-number" content="3.6.0">
<meta name="ajs-build-number" content="XXX">
<meta name="ajs-remote-user" content="someusername">
<meta name="ajs-static-resource-url-prefix" content="/confluence/s/en/2155/5/_">

There are a few utility functions that can be useful:

AJS.Data.get("some key") ex.AJS.Data.get("remote-user")

AJS.params.somekey  ex. AJS.params.loggedInUser

and if you want to see list of all available params in FireBug console just write
AJS.params and magic happens. You can get info about the current user's username, the locale or the app context path. Please note the depending on the version and the app that you are using like Confuence, Jira or other you will get a lot of params in the list that are version or app specific.