Ken, good question.
First of all, I do it for myself. When I did my EE degree, I did not have much time to do a lot of experiments with basic chips like 555 or op-amps. Blogging about that stuff is a way for me to try obvious circuits that I never built before. I document what I do as much as possible so in the future, I can read my own post to see how I built circuit x or y.
Also, I do not have much opportunity to write english text, so it helps me perfect my english skills. (I spend a lot of time looking in french-english dictionary to find how to say things)
When I first learned about electronics, I really did not know where to start and was alone in this quest. I'm sure that with a little help, I would have learned what I know now twice as fast. So I think that putting all kind of information about electronics in one spot can help some newbies. They can read a little bit of my article every week so they have a clear learning path. I try to explain things how I would have liked to learn them, so I hope it can help at least some people out there.
Finally, it is just a hobby and a way to spend my time. Better than spending the evening watching reality shows on TV in my opinion.
If you have any feedback, I would be glad to hear it.
Thanks,
Fred