@Utu

Regarding Firefox/Iceweasel urlclassifier3.sqlite - I keep it 30 Kb. I wrote in some of my other post a way to disable the growth of urlclassifier3.sqlite, but it requires alternative security measure.
urlclassifier3.sqlite is a file used by Firefox to keep a database of malicious sites containing phishing and adware. It can be easily disabled, but you will need alternative protection. The best way so far is using opendns DNS servers. Once you subscribe with them you can choose what kind of protection you want for your browser.Phishing sites are blocked by default with opendns. So thir security is way better then using urlclassifier3.sqlite and you have the added bonus of getting rid of this ever growing file. OpenDNS service is totally free