In France the Orange Mobicarte prepaid PAYG simcard was tested. Though the cheapest at the time of writing, Orange has implemented a few sneaky measures which can zero your prepaid / prepay balance at lightning speed.
The Orange 3G Internet connection worked within 48 hours after being registered using a passport copy. Orange Mobicarte comes with "unlimited" Internet access (Internet Max) for a day for € 3,-. It starts at the hour of activation for 24 hours.
There's one big catch : The flat-fee rate applies only for internet access on your mobile / cell phone - not on a laptop, notebook or netbook. In case you try it anyway, every Kb / Mb you download / upload is taken from your prepaid balance.
Read more: http://www.laptop-junction.com/toast/content/micro-wifi-hotspot-nokia-n95-iphone#3G_wireless_WIFI_hotspot_experience