USB power switch + current meter

I need a 240V switch that can be controlled via USB, also being able to measure the current flowing (or at least the presence/lack of some current) via USB. Linux compatible of course :) Ideally this switch would have a dead mans reset too - my linux controller would need to send an 'on' signal every (say) 30 seconds or it would turn off automatically. Any suggestions? I could probably build the 240V logic myself but aren't qualified and it would suck if something caught fire etc because I did something stupid :) Thanks James