This plugin contains a collection of more or less useful JQL functions that might help you creating complex queries in your Jira instance
Included JQL Functions
formatString: The equivalent to Java's String.format
formatDate: Allows you to specify a DateFormat that will be applied to the current date. For more information about available date formats take a look at this documentation.
dynamicString: Allows a combination of String.format and DateFormats. For more information about available date formats take here, examples can be seen here.
If you don't have a clue how to use those JQL functions yet, I strongly advise you to take a look at the examples.
Roadmap
Take a look at the current issues at Bitbucket.org. Past releases are listed here.