Investor Relations - IR
  
The outreach arm of a given (usually public) company.
It's someone who serves as the communications intermediary between the company's CFO and the rest of the investing world, i.e. more or less the owners of the company.
The IR person hosts the quarterly conference calls, files the proper filings, and answers generally inconsequential questions from investors which aren't so telling that they'd pierce the Regulation FD veil.
Think of the IR person as a kind of role like the Vice President of the U.S. Lots of good coffee and nice seats at the table, but little say in what actually happens.