There are several ways to go about transferring 8mm, super 8mm, 16mm, etc. to digital, and ultimately to DVD if that's your goal. You asked about 8mm, so I'll just answer for 8mm.
Elmo used to make an 8mm telecine transfer machine. They show up on ebeigh from time to time. They usually sell for $1500 to $2000. You run the film just like in a normal projector. The machine projects the film onto a ccd cell, and the output is typical VHS quality output. You can feed this just like a live TV broadcast into something like the Phillips DVD burner that has recently come available, but the quality won't be very high (typically around 250 to 300 lines per picture). The Elmo units have a frame per second and shutter blade combination that synchs the film to the TV signal. The closest easy synch for 8mm is to run it at 20 fps with a 3 blade shutter, but I don't know for sure that this is what the Elmo unit does.
Goko used to make a Telecine Player model TC-20. There are 8mm and Super 8mm models. You can pick these up on ebeigh too. They usually sell for $1000 to $1400. The Goko units are also similar to projectors, but instead of projecting the image onto a ccd cell, they project the image so that it appears to be floating in air inside the machine. You use your own video camera to capture the image by alligning it with a little window on the back of the TC-20. The interesting thing about the Goko units is that they use a 24 facet prism as part of their projection system, and for some reason they will synch with the TV at any speed. The range of speeds on the unit is typically from about 16 fps to about 24 fps. If you use the Goko approach, you can get a 3ccd cell camera, like the Canon GL1, XL-1s, or similar, and you can then get a digital file that you can run into your computer via the fire wire port. Resolution for miniDV is about 500 to 525 lines per picture. It holds up pretty well, even on a 54" TV. The Goko units are still supported in the US, so if repairs are needed, there is a place to send them. If your Goko and camera are properly adjusted and properly lined up, you can get very high quality by this approach.
Another approach is to use an 8mm projector with an adjustable speed control. If the unit has a 3 blade shutter and you can adjust it to run at 20 fps, you can synch with the TV. Normal 8mm projection speed is 18 fps, so this is only a 10% difference, and it isn't noticable to most viewers if there's no audio to deal with. You project the image onto either a telecine transfer box (mirror and ground glass), or onto a white screen, and you capture the image with your digital camcorder, like with the Goko unit. You typically project the image to a size of maybe 4" or 5" square. With the high quality digital camcorders, if you use the ground glass approach, resolution can be high enough to show the ground glass texture, so some people prefer to forget the telecine transfer box and just project onto a clean white sheet. If you're using the telecine transfer box, your camera will be at an angle of approximately 90% to your projection. If you used the clean white sheet approach, your camera will be located very close to the axis of the projector lens.
If you are interested in this general area, you can go to Google and do a search using the key word "telecine." There is another method that I have not used that involves frame by frame capture using a specialized set up that is being sold over the internet. I haven't looked at it recently, and I've never tried their gear. They are very negative about the Elmo and Goko methods in their literature - but my experience with the Goko is that the negative hype that this guy publishes is based on the results you get when your Goko lamp and camera are misalligned. The web page where this method is discussed is at http://www.moviestuff.tv/8mm_telecine.html.
FWIW, I would pass on the Elmo telecine transfer units just because of the modest resolution. The video camera chip in these units is about 15 year old technology. My prefered method is via a 3ccd mini DV camcorder and either the Goko or the variable speed projector. You can get good results with either method. The one thing to watch out for is that most of the folks who are selling projectors on ebeigh seem to be overly optimistic about the functionality of their unit. These old projectors can eat the film and ruin your stuff pretty quickly. It is for this reason that I finally settled on the Goko TC-20 for my own 8mm film to DVD transfers.