If you can get a big enough following from customer lists and newsletters you might want to start your own forum. But I always see people trying to start a forum and it falls flat on their face, mainly because they make it too big and they never promote it.
The main reason is because nobody eats in an empty restaurant. Don't setup a "multiple topic" forum like phpBB where it allows you to partition the thing off into different subjects. You have to start small, get enough traffic to that forum for THAT type of forum to become self-sustaining before you build bigger.
By that I mean start off with a blog.
This blog (and eventually your message board) HAVE to have a niche. You can't just have a general purpose hang-out message board, or have it based on something really vague like "Marketing," or "Finance," or "Computers." Instead go for something specific like a Copywriting message board. Or a message board about home loans. Or a message board about digital video.
You supply all the posts, and any user "posts" will just be comments to this journal. Don't require any sort of signup in order to post.
Give people an option to sign up for e-mail updates but DO NOT use the autoresponder built into the blogging software. Instead use a separate autoresponder script. Why? Two reasons:
1.) You can write a quick teaser message that will entice more subscribers to read your posts than any boring automated notice could.
2.) This way it will be easier to move subscribers over once you graduate from a blog (keep reading).
(WordPress works great for this and is free.)
Start off allowing anyone to post, but once you start getting traffic to that page and the blog spam starts rolling in you will either have to require approval by you for a comment to go through or require the poster to type in a code to prove they are human (you've seen the kind).
It will be easy to get SOME traffic to the blog, if you keep most of your entries to it in article format, because then you can submit these articles to ezines and the article directories with a link back to the blog.
Keep the blog format going, be SURE to post regularly and if possible write content in advance (Post To Future) so that if you miss a week your content will still be updated as if you never left. If you feel ambitious setup RSS feeds for the blog and submit to the feed directories.
Continue posting until you reach the point where after you make a post, you receive comments from 10-20 different people within a day or two of the post. This 10-20 has to happen without any e-mails being sent out, or any kind of active promotion.
Until you reach this point stay with the blog, it means you haven't reached critical mass yet and any attempt to change over to a more complex kind of site will never work.
Once you've got those 10-20 spontaneous posts you can go ahead and make the move from a blog to a forum. But be very very careful. There are a lot of things that can go wrong, especially if your forum doesn't "unfold" properly, which is a technique I'll discuss with you in Part 2 of this article...
Free (humorous) video for you about how to promote an affiliate program without seeming spammy. Take a look: http://www.affiliatebattleplan.com/Rewrite.html