cipaf provides the IP accounting information from cisco router in human-readable form; collect it in to the HTML reports on daily or monthly basis.
Click is a modular software router developed by MIT LCS's Parallel and Distributed Operating Systems group, Mazu Networks, the ICSI Center for Internet Research, and now UCLA.
flow-tools is a set of programs for processing and managing NetFlow exports from Cisco routers.
Gargoyle Router Management Utility
Gargoyle is an interface for small, widely available routers such as the Linksys WRT54G series and the La Fonera. It provides functionality above and beyond what the default software provides including sophisticated dynamic DNS, quality of service, and bandwidth monitoring tools. The primary goal is to provide a polished interface for these advanced tools that is at least as easy to configure as any existing firmware. This project is based on top of OpenWrt, but unlike other Web interfaces for OpenWrt it places a strong focus an usability and is meant for average users, not just power users.
Minimal-router is a router containing only the neccesary tools to setup basic networking and firewalling. It aims to be easily configurable while staying as secure as the linux kernel itself.
ulogipac is a powerful IP traffic accounting tool for linux routers and hosts. You can use the power of iptables rules to specify which traffic you want to account and which *not*. The size of IP packets sent to ulogipac through iptables is counted and buffered.
WANdoc Open Source
WANdoc Open Source generates interactive documentation for large Cisco networks. It uses syslog and router configuration files to produce summarized, hyperlinked and error-checked router information.