I'm like Technotiger, I switch my computer off every night but leave my Netgear DG834GT on 24/7.
The reason I do this now is that with a previous ISP (ZEN) I would power my router down before retiring for the night, when I powered it back on my line was syncing at a lower profile (5000-5500 kbps) where as before I switched it off it was syncing at the full 7150 kbps. The line profile went back up to 7150 after a few days though.
Powering a router off and then on again is actually re-setting the router each time, a router should only need re-setting if you are having problems with it. Certainly with my BT Homehub it is very much better left on 24/7.