It's no secret I'm fond of webcams from around the world, and I'd forgotten about a little gem I downloaded long ago: WorldView+. As far as these apps go, WorldView+ has possibly the best design of all of them. Also, like many other webcam apps, it has some missing cameras (although it touts 10,000). But I have yet to find one app with the most comprehensive camera lists -- all are a compromise. That said, WorldView+ is one of the more functional and attractive "compromises" out there. Plus, it looks great on the iPad or iPhone.
The buttons at the bottom allow easy access to your bookmarks, perform a search, look near your current location for cameras, and discover random or featured cams. These are the basics, really. What distinguishes WorldView+ are little touches like providing a wealth of info around each camera -- Wikipedia articles, weather at that location and even an image taken during daytime (local to that camera), which is nice when you happen upon a camera that shows nothing but darkness. There are a number of streaming cameras set up, and a few that will provide a time-lapse view.
For some reason WorldView+ missed a few cameras I found otherwise, and it seems to focus primarily on landscape cameras. World Live Cams had a few cameras I didn't find in WorldView+, but overall WorldView+ is a better app as it is more complete and packed with useful features.
As with any properly-designed app, bookmarking cameras, finding info and basic searches are all done with a minimum of fuss. Map view is a joy to use, and it looks great. Zooming around the map, then into an image, then zooming into that image makes you feel a bit like transporting around -- or at least like you have access to a vast array of surveillance cameras. While there's always more that could be done with any interface (Tapbots apps do this well), the core functionality of most cam viewers is encapsulated within WorldView+ and all for a reasonable $2.99. If you like webcams, you'll really enjoy WorldView's features and design.