Lots of people mount their lights on their heads. It works well for them. It's important not to shine them in people's faces, so if you're conscious of that, it can work out well.

I use a spoke light when I ride at night. It's not bright, but the motion makes it very noticeable. It uses a pair of coin cell batteries. I use it as a supplement to my two taillights. I tried using a spoke light in my front wheel, but it distracted me too much, so I just use one in the rear wheel.