What a cool idea, Jo! You've already pasted my favorite, Old Faithful, it has a bunch of great memories for me.
Also at Yellowstone is the Mammoth Hot Springs cam:
http://www.nps.gov/archive/yell/tour...ammothcam2.htm
There is also the FishEye cam out of Coral Gables, FL:
http://www.FisheyeView.com/FVCam.html
Here is Niagra Falls:
http://camping.about.com/gi/o.htm?zi...lls_Webcam.htm
Crater Lake NP in Oregon:
http://www.craterlakelodges.com/pres...-818_1394.html
The Rocky Mountains' Kawuneeche Valley cam:
http://ns.www.nps.gov.edgesuite.net/.../grlk_cam.html
Man, there are just so many!