The Gude Expert Power Control NET switch is an ethernet controllable power socket. It an switch a single socket. It sells for about 125 Euro.
It can be controlled by HTTP although it uses GET requests wich breaks idempotence. Still: it works:
curl http://admin:email@example.com/SWITCH.CGI?s1=0 > /dev/null
One nice thing about the Switch is the fact that it supports DHCP.