[Hampshire] Disk space tracking/du comparison

Hi,

Does anybody know of any tools/scripts to track disk space usage or
"compare" du output over time?

I'm trying to track where the disk space is being eaten on a machine, I've
got a du output from yesterday and today, when around 19G of free space
"disappeared" from the drive...

Yes I could just manually compare it but that will be a repetitive and
time consuming task, or write a script to do it myself, but why re-invent
the wheel if somebody else has done so already?

So anybody know of anything?

Andy