Have you thought about a purple martin house? They are voracious mosquito lovers, and easier to attract, I think, than bats. Even here in the urban bat capital of the world, bat houses can go unnoticed. The only requirement for purple martin houses is putting doors on them until the martins migrate through (so the sparrows don't set up house ahead of time)

Our backyard is a mosquito-haven too, and I don't quite know why! A purple martin house is on our to-do list.

I don't know much about attracting bats but I did hear that they can eat their weight in bugs. I imagine thats a lot of bugs. We don't have a bat house but I have definitely seen them in our neighborhood often.

The purple martin house is also on our to do list. Aaron has wanted one for awhile now. Of course he is the mosquito magnet while I they hardly bother me.

I have heard - though I don't know any more than hearsay - that it's extremely difficult to attract bats. One thing you may want to try is guano in and around the bat house. I've heard that you can have some success with that.

Although I checked the tubes, and this page says that guano is not a sure-fire thing. They have lots of good tips though.

We bought a "mosquito" plant (Pelargonium citrosum) from Home Depot and put it on our patio. We haven't had mosquitoes around our patio all summer -- not sure if this is because of the plant, but we will do this again next summer!