Trafficlogger is a tiny program which logs your traffic from each device that is listet in /proc/net/dev. It logs all traffic (TCP, UDP,...). It is written in ANSI-C and should compile and work on nearly all Linux distributions.
SrvReport is a simple and featurefull server monitoring and reporting
system. It will send every day a mail with the latest
state of the server including traffic (via /proc/net/dev and/or iptables), cpu, mail, http, ftp reports
and other logs.