This paper presents /nailon/ - a software package for online realtime prosodic analysis that captures a number of prosodic features relevant for interaction control in spoken dialogue systems. The current implementation captures silence durations; voicing, intensity, and pitch; pseudo-syllable durations; and intonation patterns. The paper provides detailed information on how this is achieved. As an example application of /nailon/, we demonstrate how it is used to improve the efficiency of identifying relevant places at which a machine can legitimately begin to talk to a human interlocutor, as well as to shorten system response times.