How to get rid of bats
OMG! There's a bat in my house!
Alright, don't panic. Bats are typically as scared of you as you are of them. The problem is they can't see very well, so they aren't exactly sure where to go to get away from you. If the bat is in a room with windows, try opening the window (and the screen, duh) and closing the door to the room. Leave the light on, as bats usually prefer darker spaces since it gives them an advantage over both predators and prey because they don't need their eyesight to know where they are going.
It didn't work. The bat is just sitting there!
Some bats just don't want to leave. They'll probably find something to roost on and just stay there, scared as hell from all the commotion they've caused. Your best option here is some gloves and a fishing net. Try to capture the bat in the net, take it outside, and carefully release it. Bats are very fragile creatures (those "veins" in their leaf-like wings are just small bones). Don't kill a bat deliberately, as they are quite good for keeping down the insect population (much better than frogs) and they love moths, which happen to love chewing holes in my clothes.
I can't capture the bat, now what?
Bats go out to feed at night. If you can find out where they've set up camp in your house, spray it down with a cat and dog repellent when the bats go out to feed. DO NOT, under any circumstances, spray a bat directly with that stuff. They won't die, they'll just get really irritated. You don't want that. Another option would be to put up insulation in your attic where the bats likely are staying. Bats don't like rubbing against fiberglass insulation any more than you do. You can also try to find where the bats are entering your house and seal it up at night while they're off feeding on the neighborhood moths. If all else fails, call pest control, they'll know what to do.