Many of the big makers are including this service with their routers( not all free). You will not get one that can turn off at a set time but you will be able to set time frames for going online and limit the amoumt of time online and even track which websites are visited, with password protection. Some are the
Buffalo WRB-G54K
Netgear WPN824 router
Linksys Wireless-G Router WRT54GS
Belkin Wireless G Plus MIMO Router
Cnet has reviews on all so you can read about them and you can also check their website and see if there are any different ones that better suit your needs. Hope this helps.
I need some help, I am looking for a wireless router that I can set to turn off and on at certain times. I am looking so I can control when my kids are allowed access to the internet. I would also like to password protect it too.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic