If my telco is to be believed, I've been burning through ~150Mb/day since the start of the month with my phone being in my pocket / sat on the side at home (within hearing distance of my WiFi).
My email accounts are set to sync once an hour, but I've not been having excessive amounts of email (maybe averaging 3/hour over two POP3 accounts, and 1/per 3 hours for GMail).
My background tasks are all disabled, and I even closed all my tabs in Internet Explorer just in case; but can I find out what is causing this excessive data usage? And any ideas why it has only recently started happening?