Anyone else having a gnat problem?  By "gnats" I mean tiny winged creatures that aren't house flies, termites, mosquitoes or any other winged creature.

I've cleaned, vacuumed, emptied trash, cleaned out the trash cans, gotten rid of old fruit of veggies and poured ammonia down the drains.  For a week I thought I had them beat, but now they're back.  I've killed 8-10 of them in the last couple of hours.  They're driving me freaking nuts.

Any suggestions before I call an exterminator on Monday?

Do you have any house plants?
That's usually a big draw for them, especially if you overwater them.

Also any standing water, like a terrarium/fish tank.

We have house plants, the wife threw some out the first time we noticed gnats and now she's looking at the others.  No fish tanks or other standing water other than the toilets, and they get flushed pretty regularly.

I've noticed them at my mom's house this year.  She's a clean freak so it's not a sanitation issue.  She has a lot of house plants but that's always been the case.