If you're not aware of this you should be!!!
Just yesterday I found I had 4 GB more space on my HDD than normal, and to put it lightly I was shocked! I mean, 4 GB is quite a large sum to just disappear without notice or at least someone letting you know, right?
I finally realized what it was. The other day, I decided I was tired of seeing the HL2 Demo and CS source demo on steam, and I found you could delete them. What I didn't know, is that steam preloaded both of these, in full on my HDD, thereby chewing up my bandwith and HDD space without asking or even letting me know
Is it just me, or is this complete and utter bullshit??