Okay, let start with a product that I've used previously and got more of for Christmas. It's the MEC turtle light. These little babies are great! Cheap, bright and so far long lasting.
They're a single LED flashing or stead light with an elastic mounting band. I've had one on my fixie for a while (I don't want to clutter up that bike with anything, so this is a great option for winter illumination) and it's worked flawlessly. I also have one mounted on my helmet for the past month and a half, and I really notice that traffic notices me more. One great thing about having one of these mounted on your helmet, is that even if your main light are being blocked by cars, people waiting to turn out in front of me, have yet to miss the flashing bulb up top. I also aim it right at their eyes to make sure they don't miss it. A new addition to the helmet is a red one on the back. Unfortunately I can't aim this in their eyes, but I do think that it makes me more visible from behind. I've been told (by one of my co-workers) that when following me, I show up well, except when on-coming traffic's headlights get close. I guess the lights on my bike seem to disappear when next to a car head light. A light up on your noodle is less likely to do that. The elastic also makes for quick mounting to handlebars, seat post and loads of other applications.
I received 6 for Christmas (3 front and 3 rear) to bring my total up to 8. I still would like more, they are just really cool little lights with a whole whack of uses. Most recommended. At $3.50 CDN, they are a great value also.
Here's a quick video of them in flashing mode on my lid.
I'm not sure how ordering works (I think they can be ordered up from the US) but the website should let you know what you need. You do need to buy a membership ($5.00 for life) to MEC prior to purchasing, but I have found that it is well worth it. If you get a chance, get to one of their locations in Canada.