Long exposure.
If you can, set the camera to Manual mode (or whatever is close to it) and set the exposure setting to around 1/2 to 1 second long depending on conditions, ISO sensitivity around 300 or so, and play around with environment and white balance.
Long exposure time obviously necessitates (spelling?) the use of tripod for the camera and perfectly still scene, but it produces good effects!
Laser in question is about 80 milliwatts of output power, in a normally lit room during daylight.
Also, high res image I didn't downsize,
Eudaimonium on deviantART - click the image or download it from the link on the right to see full res.
Lasers are 80mW and 150mW (or so).
I don't have a smoke machine and nobody in my house smokes, just for the record.