Connection Bandwidth Metering?

[Chris Telting]

I have my own Virtual Private Server (VPS) and was wondering what is the 
most straightforward to meter my own connection?

I would like to email notices to myself of excessive bandwidth usage as 
well as take steps that limit a DOS attack or Slashdot effect on the 
webserver.  I would also like the metering to be persistent as possible 
across reboots.  Not really looking for full logging or to do graphs 
yet, just want the current metered bandwidth.

Thanks