Indeed there is, and it's right here on this site! It's a feature we introduced back in the summer of 2008, due to popular request, and which we've maintained ever since.
There have been many additions and subtractions to the list during that time, with some "construction cams" being temporary by nature, in place only for the duration of a project. For example, SLS had a construction camera from specialists TrueLook.com for the duration of the Sahara makeover, but now that the project's been completed, the webcam is no more. We assume the same will hold for MGM/AEG "ArenaCam" that's currently monitoring the progress of Las Vegas' newest indoor stadium. According to that site, however, as of today there are still 465 days remaining until completion, so it looks like that webcam won't be going anywhere soon.
Other webcams have come and gone with the venues that housed them, such as the one-time Hawaiian Tropic Zone camera that offered decent views of the Strip from outside the Miracle Mile Shops. Other notable losses include a quartet of cameras that once operated from the roof of the Imperial Palace, and a hi-tech pan, tilt, zoom affair at the Springs Preserve, to cite just a couple of examples.
Still, there have been plenty additions to the list over the years, too, and to the best of our knowledge, you can currently catch the tourist buffoonery at the "Welcome to Las Vegas" sign; both the Bellagio fountain show and the display in the Conservatory; the Silverton aquarium; current conditions on Mount Charleston; the goings on on Fremont Street; and live all-nude strippers, among other options, all from the comfort of your armchair! Here's the link to our current list of active Vegas webcams; note that some, like Boyd Gaming's individual property cams, require free sign-up in order to view. If we're missing any, or if you find a dead link, please let us know!
