Fungus gnats are also an issue if you keep indoor plants.

I recently discovered that you can water your plants with mosquito dunks in the water, which will put the bacteria (aka: BTI, bacillus thuringiensis strain BMP 144) contained in the dunks into the soil. The bacteria then paralyze the larvae growing in the soil and they die.

Doing even more research, it seems there is a newer strain of the bacteria (AM 65-52) that you can buy in 16lbs! buckets for $570 off Amazon (or people have broken it into smaller batches on ebay).

This stuff really works like magic. Once the adults die off, no more appear.

Gnatrol Biological Larvicide Fungus Larvae