Piles of junk building up in /var on persistent Live CD installation

[Chanchao]

I spent a couple hours yesterday why I was always out of disk space on
my 'casper-rw' persistent Live CD partition.  In the end I booted
normally (non persistent) and did some serious "du'ing" and found an
incredible pile of junk in /var.  Surely this is not the desired default
behavior for a Live CD installation where space is very limited?  For a
regular server install I can see why you'd want log files and all that,
but not really when you're running on a 150 MB usb memory stick
partition!!

Is there anything I can do to turn all that logging and caching off?  

Cheers,
Chanchao