We have BT, started at 10GB which never seemed to be quite enough so we upped it to 40GB.
Regular internet search usage and emails. Very occasional iTunes downloads (maybe 2 albums worth a month on average) occasional iPlayer usage on iPad (maybe 2 hours' worth a month). No online games via consoles.
Last 2 months we've been charged extra for going 3GB over. Is it just that regular websites are so heavy on flash and mini video clips (MNHQ I'm looking at your Beko ads here....)