Explore.org has a very relaxing live feed of bears feeding on salmon at Brooks Falls in Katmai National Park, Alaska. At night, they run a highlight reel. Great for having on as you work.
If that's not to your liking, they have many others, including a Great Dane nursery cam:
And a very noisy osprey nest in Wyoming:
• bears | brooks falls – katmai national park, alaska (via The Atlantic)