I've got three powersupplies that I am using on 2 Raspberry Pis, depending where I am. All of them are rock solid so I will offer them as possibilites (available in the UK for UK 3 pin).
The best one is the Masterplug with 2 USB sockets 1Amp, it has some form of surge protection in and is the one I use for my permanently online Pi. It doesn't occupy a socket as it can be stacked. I got mine from Sainsburys for £5 when it was on promotion, but they are £10 here:
http://www.screwfix.com/p/masterplug-su ... lack/28341
Then another Masterplug one, simpler in design with single USB and has been solid for me, with Keyboard, Optical Mouse, network (ethernet), HDMI and occaisionally with WiFi in the USB (£6.99):
http://www.screwfix.com/p/masterplug-us ... lack/45307
The last one, I got last week from Wilkinson for £6.50 and I am delighted with it. £6.50, 1Amp, single USB and it again has been rock solid.
Can't find it on the Wilkinson website, but it is branded "Groov>>E".