If there is a small artificial water body around that is a mosquito breeding ground, then Gambusia or guppy fish can do the trick. Guppies are available very cheaply from aquarium shops as they are used as food for larger carnivorous aquarium fish. It would not be advisable to release them in a natural water body as they breed exponentially and might overrun any native fauna (if present).

Citronella works well in two forms - as a spray and as an oil in a diffuser. I have used both. The spray is commercially available and works well for personal use or for use in a regular sized room. The diffuser is a more "fixed" method - add a little citronella oil to some water in a small heating container (like a katori) and place this over a small flame (like a candle or a lamp). The water heats up and the oil vapourises slowly (you can start to smell it in a few minutes). Using the diffuser for just about an hour or so in the evening works remarkably well.

However, I think you're looking for a larger scale alternative than a personal or household one. Always, the very best thing to do is to simply keep the neighbourhood clean. Bottles, cans, plastic boxes, bags, tyres etc. lying around are a delight for mosquitoes.