You can get email and text alerts for almost anything nowadays—even one that tells you when the International Space Station (ISS) is overhead.
The ISS is the third-brightest object in the sky—it reflects light from the sun, and is visible even when the moon hasn't risen—and looks like a fast-flying airplane (though of course it's much higher, and is flying much faster, than any plane). It's so bright you can spot it even when you're in a light-polluted city. By signing up for NASA's "Spot the Station" alert, available both as text messages and emails, you can find the best time to see the ISS.
Depending on where you're located, you can see the ISS from once or twice a month to several times a week. (Or not at all: NASA notes that, because the ISS orbits at an inclination of 51.6 degrees, "the farthest north and south of the Equator it will ever go is 51.6 degrees latitude. If you live north or south of 51.6 degrees, the ISS will never go directly over your head—this includes places like Alaska." You can see a list of the spotting locations here.)
The alerts tell you what time to expect the ISS, where it will appear in the sky and at what height, and how long it will be visible. They look like this:
SpotTheStation! Time: Wed Apr 25 7:45 PM, Visible: 4 min, Max Height: 66 degrees, Appears: WSW, Disappears NE.
Sign up here; over 300,000 people already have.