What settings are best for low light outside?

I'm using Nikon D5000

Added (1). Thanks for such awesome answers!

There are no best settings really.

Just use your fine cameras light meter to determine the exposure setting. If the indicated shutter speed is under 1/250th second, use a tripod. If the indicated shutter speed is below 1/15th second, use a remote shutter release.

Here is a shot outside using an ISO of 3200, necessary to capture the action without any blur.

Pretty loaded question.
What are you shooting?

Depends on the look you are trying to achieve. If you want to still keep the shutter speed up, with little light coming onto the sensor, to get a 'correct' exposure, you'll need to increase the ISO and open the aperture as wide as possible.

If however, you're going for the long exposure shot, you will need a tripod. Once the camera is on a tripod, you can let the shutter speed go as long as it needs to. That means you can set the ISO as low as it can go (for best image quality) and select the aperture you want for depth of field. Then just either have the camera in A mode for shutter speeds up to 30 sec, or if you need longer than that, then use bulb mode & keep the shutter open as long as necessary.

Couple of points to remember for long exposures;
- use a remote release to trigger & lock the shutter open in bulb mode.
- if the exposure is more than 30secs-1min or so switch the Long Exposure Noise Reduction ON (otherwise keep it off) - the camera will expose a 'dark frame' for an equal length of time as the original exposure
- make sure batteries are fully charged before very long exposures - they've got to work the camera not only during the exposure, but also the dark frame exposure too.