rules2mrtg is a tool that creates MRTG data traffic graphs derived from iptables's internal traffic statistics for the local machine for every configured IP number/ethernet alias. You can also define ports or port ranges to be monitored per IP address. This avoids problems with using SNMP and aliased interfaces.
Pkviz is a tool for plotting and cycling through and animating a series of network packets captured by tcpdump. What makes it unique is that the packets’ structure is visualized, not any labels and not time itself. Pkviz takes each byte in a packet and plots it out end-to-end, left-to-right, from the first byte to the last. How high the dot gets plotted depends on the value of the byte: bytes with a value of 0 are at the bottom and those which are 255 (0xff) – the maximum value of a byte – get plotted at the top. This might not be interesting for one packet, but that changes when you start looking at thousands of packets. Pkviz can cycle through thousands of packets in the set so you can see what happened on the wire.