Cool Website: amionline.net
Often I find myself asking, "is this website taking a long time to load, is something wrong with my browser, or has my internet connection dropped again?", and amionline.net helps narrow that down. It's just a static website that says "Yup. You're Online", designed mostly for guest WiFi captive portals that don't play nicely with https. It's a surprisingly useful way to determine whether you're actually connected to the internet in any meaningful way.