If the firm is discussed in Chambers & Partners http://www.chambersandpartners.com
then it is likely C&P will mention big deals that the practice group has been involved in, as well as the star attorneys. Vault often includes this info--your career services department at school should be able to provide you with Vault information. Otherwise, try the firm's website, google, reading attorney bios, etc.
Learning a little bit about an important deal or case is one of the best ways to show genuine interest, impress your interviewers, and keep the conversation going, in my opinion.