cat eye lights that run on two watch batteries (no looking for crazy batteries for cameras or anything) and are turned on by using a magnet. That is on a laynard. It works by using the laynard and the actual light to fasten it the bike, helmet, etc. It is great so that you can attach it to whaever you want as long as it is going to fit.
The lights I got are
While looking around the blogosphere, I have come over a ton of people talking about lights recently, as it is that time of year again. I recently got new lights from work, and I wanted to really try them out tonight. They are really just lights to be seen with, not really for seeing too much. I have lights for seeing, but I think they are a bit blinding to folks. Since I live in the city, it is pretty much bright all over.
The fit on the bike was pretty good, as it is tool free, and can go over anything at all. I had to put mine over some cables on the front of my bike. You can see in the front picture that is attached over the cable. The rear is just around the seatpost, but it can go anywhere.
The lights functioned well, and I think if I lived somewhere with less light, I would have seen how bright they actually get. I rode allover downtown, then went to a pretty dark park on my commute. Over all, I am very happy with them. I think I may get a few more pairs for other bikes. They are about $24 for a pair(they come as individuals and white is more expensive than red) from your LBS.