XWall has an interface to collect real time statistic data that can be used to feed another program which then creates a graphic out of the data.

The state-of-the-art program for this purpose is MRTG (Multi Router Traffic Grapher). 
MRTG generates HTML pages containing GIF images which provide a LIVE visual representation of XWall's data.
More info on MRTG at http://oss.oetiker.ch/mrtg/

Below are some samples from a live XWall: a Compaq Double PIII 900Mhz, 512MB RAM, 36GB SCSI Raid 5,  that processes app. 90000 messages with 10GB a day.

Inbound and outbound SMTP messages per hour

Blocked and Spam messages per hour

Greylisting per hour

Inbound and outbound SMTP bytes

Inbound and outbound SMTP queue

Inbound and outbound Exchange queue

Inbound and outbound connection count

Central European Time ( UTC + 01:00 )