Over the years, Alek Komarnitsky has has to chase nine bats out of his house. He's documented each encounter (with photos) on his website.
As of July 27th, 2006 I have had nine "encounters" with bats in my house the last five years … and the score so far is "Alek-9, Bats-0" … although 7 of the bats were "returned" back outside … so it's possible I've had some repeat visitors. I wish I knew why/where these guys are coming from, but I really wish those pesky critters would stay outside and eat the bugs. BTW, if you have bats in your house, the first thing you should do is go get your digital camera (like I do! ;-) … and then close the doors so they are confined to that room – then deal with 'em!