Be prepared for technical questions that involve programming without much testing (no compilation, IDE-like coding environment). Articulate your thoughts throughout the process of solving the problem(s) presented. This helps the interviewer understand your problem solving and logical reasoning skills. The "Cracking the Coding Interview" book by Gayle Laakmann McDowell is an excellent reference for most of the potential topics that an interview will cover. Also be prepared with questions for the interviewer! They're interested in talking to you assuming you have appropriate questions prepared.