[smikolay]

I've been playing with toggle (www.togglemobile.co.uk) as it covers more countries than Tru. They use their parent's MVNO network (Lyca Mobile), and actually manage decent prices in a number of European countries (and free incoming calls in a number more around the world).

The data offering isn't as wide spread, and they currently only offer per MB outside UK; but still a better deal than roaming.