Bat boxes!

Bats are really wonderful creatures. I've always loved them. I remember years ago there was a great number of them, and during nighttime it was very common to see them flying around in the suburban areas. I remember long bike rides during summer nights watching them, and it seemed impossible to see them during daytime. That was because they are very shy creatures, and they are able to hide very well.
Too bad that at the moment bats are endangered animals. This depends on many factors: pollution, the difficulties for them to find a decent place to roosting, pesticides, ignorant and cruel people persecuting them.
The reduction in the number of bats is really bad news for everyone. First of all, because they are lovely animals. Then, because they are useful too. They are great impollinators, and, for people who fear mosquitoes, they can eat up to 1000 mosquitoes in a hour. Mosquitoes are not a problem for me, I respect them too, but I know lots of people that can't stand their bites.
Anyway, we all can help bats placing a bat house outside our house. You can buy bat houses in a variety of shapes and sizes, or you can biuld your own, and it will be very inexpensive.
Here and here you can find two tutorials for two different types of bat houses. A good video tutorial can be seen here.
(I've been a lazy guy and I bought an assembled bat house at a local gardening shop, they are not expensive at all, so if don't have enough time for homemaking it, buying one is a good idea)