This is the source of my weather data feed. It is (obviously) a Davis Vantage Pro 2. Cost a bit more than other brands I was checking out, but the reviews I found kept suggesting this over others and I have subsequently found it to be an excellent station.
I have it connected to a data-collection computer (currently an Intel Mac Mini running Debian) which uses the wview package to log data and produce the web pages for the feed. The system has been running since February 2009.
The only glitch I have is a bit odd/interesting. After at least a few days of dry weather, if it starts to rain slowly the wview daemon that actually pulls data from the station will lock up, sending the system load to 1.0. The weather station itself is fine, and restarting wview gets things working again. This doesn't tend to happen if the rain suddenly starts pouring down, or if it was recently raining (start/stop several times per day). I haven't found anything in the logs to suggest what the issue is, and got no response on the mailing list.
Fortunately, the interface module for the station will keep collecting data for up to a week until the computer talks to it again, so no major issues - just a minor annoyance. I may just automate the restart - I think the software package may even support that already - but haven't done it yet.
This model is a wired unit - meaning there is a phone cable running up to the outdoor sensors. With it also tethered to the computer, that's not really a big deal, but in retrospect it would have been handy to go wireless and be able to carry the display along with me at times. Such as when I'm heading for cover during a severe storm!
The wview package can also feed data to a variety of "citizen observer" programs, but I'm not doing that. My sensors aren't mounted at the "suggested" levels - I wanted them up out of the way, so they are just above the roof at one end of the house, as shown in the picture. Anyway I'm not sure how valid my data would be overall. I'm located right at the base of a good-size hill (the hilltop is about three houses south, and is taller than my roof) so especially for wind data I don't see anything like what is measured at the airport just a couple miles away.