I needed a ride to the airport for a business trip and found this company on Google (towncar services are the same price as a taxi, and much more comfy). I was leery about booking online (the form is old school), but it turns out that I didn't have any reason to worry.
On the day of my flight, they showed up a few minutes early in a very clean and new towncar of some American variety (Lincoln, I reckon?). The driver was courteous but didn't want to chat, which was a-ok with me. I fell asleep in the backseat and woke up when we got to the airport.
The fare was $45 from Ballard, and I tipped 15%. They take all credit cards. I would definitely use them again for airport transportation.