I recommend a blog. It is extremely difficult and time consuming to get a forum going. Besides, where's the advantage for you?
With a blog you are giving the info one way. If people are interested they will contact you.
Additionally, a forum is a hassle to install (not really, if you are technically inclined, but you will still need to pay for hosting etc...) You can get a blog for free (and even host it yourself if you are so inclined) by simply visiting
http://blogger.com It will take you about 15 minutes to get it up and going.
If you aren't sure, just do both...