App to Measure Network Volume?

[Johndan Johnson-Eilola]

This is slightly off topic, but is anyone aware of an application that 
would measure the volume of data uploaded and downloaded over network 
connections on a TiBook (i.e., number of k or megs over time). I'd like 
to calculate my average data production/consumption via the network for 
a project I'm working on. (I could probably manually calculate these 
things by studiously logging every email, instant message, Internet 
radio stream, weblog posting, etc., but the measurement would probably 
affect the activities themselves.

You can reply off list to avoid pulling things further off topic. (If 
anyone is interested in the replies I get, drop me a note at 
johndan at clarkson.edu and I'll let you know what I find out.)

Thanks,

Johndan Johnson-Eilola
Technical Communications
Clarkson University

johndan at clarkson.edu | http://www.clarkson.edu/~johndan/