My Nikon D70 has been sitting around unused since I bought a Nikon D300. To make it useful again I decided to convert it to an infrared camera. After doing some research, I found that Lifepixel.com will convert your camera for you or sell you a filter to do the conversion. Feeling adventurous, I decided to do the conversion myself. Life Pixel's site offers decent directions and assures you that the Nikon D70 is relatively easy to convert.
Digital camera sensors are inherently sensitive to infrared light--they have a low-pass filter that block most of the infrared light from reaching the sensor. You can take infrared pictures by putting a filter in front of the lens that block the visible light and just lets the infrared light through to the sensor. The disadvantage of this is that so little light reaches the sensor that you end up with a very long exposure times. Also, with SLR's you can't really compose using the viewfinder anymore since so little light is going to the viewfinder. Life Pixel replaces the infrared filter in front of your sensor with a visible light sensor so the camera's viewfinder still works and the exposure times are normal.
Life Pixel offers 3 different Infrared filters, Standard IR, Enhanced Color IR and Deep BW IR. They also offer clear sensor filters and original Low-pass filters in case you scratched your filter and wanted to replace it. I chose the standard infrared filter. The filter replaces the stock low-pass filter that the camera comes with. By removing the Low-pass filter and replacing it with an IR filter, the camera is as sensible to IR as it was for normal photography. The major benefit of this is that you can see through the view finder and easily compose your shots. There is also no need for long exposure times, and no need for a tripod. This is a huge advantage over the standard way of doing Infrared photography. Life Pixel has filters for quite a few cameras. For the complete list check out their web site.