Thought this feedback might come in useful.
I have been using NetWorx for about a year now. Originally, my laptop had been the sole user of the connection (via a WiFi Access Point), but now we have two laptops that share the connection via the same WiFi Access Point.
The other week, we blew our bandwidth cap. This was no surprise, as our ISP had automatically emailed us to warn that we were approaching 80% utilisation of the capped limit. However, I had rather wished that I could use NetWorx to monitor all bandwidth utilisation for that line, but I had assumed that it could not do that except across a LAN.
Today I was playing around with the NetWorx settings on the two PCS we have that use the line, and - somewhat hopefully - I tried ticking the box in the "Advanced" tab that said "Synchronise usage data with other NetWorx instances on the network".
To my pleasant surprise, both laptops' instances of NetWorx almost immediately picked up each others' data, and on both laptops you could see the bandwidth consumption by user within laptop, or as an aggregate total for all users.
NetWorx is currently up to v5.1.1 as of 2010/04/14. This usage data synchronisation, together with its nifty reports and bar charts, make NetWorx a very good piece of free software.