AirSAM is a desktop GUI that compliments the Web based Snort Alert Monitor. AirSAM gives up to date insight into who might be attacking your network. The ultimate goal is to give audio/visual cues right at the time of the attack. AirSAM is an Adobe Air application and should run on Mac OS, Linux, and Windows.
Xplico is an IP traffic decoder that extracts data from an Internet traffic capture. From a pcap file, it can extracts each email (POP, IMAP, and SMTP protocols), all HTTP content, VoIP calls (SIP, RTP, H323, MEGACO, MGCP), IRC, MSN, and so on. It isn't a packet sniffer or a network protocol analyzer, but rather an IP/Internet traffic decoder or network forensic analysis tool (NFAT).
Yet Another Flowmeter (YAF) is a tool for network flow capture, primarily designed to operate efficiently on white box hardware and generate IPFIX flow records. It is designed to operate primarily on Unix-based systems (including Mac OS X), and is supported by the Network Situational Awareness team at CERT.
Picviz is a parallel coordinates plotter which enables easy scripting from various types of input (such as tcpdump, syslog, iptables logs, or Apache logs) to visualize your data and discover interesting results quickly. Its primary goal is to graph data in order to be able to quickly analyze problems and find correlations among variables. With security analysis in mind, the program has been designed to be very flexible, able to graph millions of events.