In the summer, you can literally watch corn grow via a web cam in an Iowa cornfield.
Right now, you can watch a black bear hibernate and, hopefully, give birth via a bear den cam. Yes, there's a camera trained on a female black bear near Ely, MN, who is about to give birth any minute, day, or week now. Or so they think.
You, too, can watch Lily, the bear, right here: http://www.bear.org/website/visit-us/lily-den-cam.html. Or if you forget all that, just go to bear.org and you'll be able to find Lily again.
This might be a good site for your grandkids!
Thanks to Bonnie for the bear tip!