The latest version of this open-source forum software allows users to upload profile pictures, attach files to their posts, and get forum updates sent to their e-mail addresses.

Price: Free

This open-source application from the makers of WordPress, the popular blogging platform, makes it easy to add a simple forum to your website. If you set up both a blog and a forum, the two programs integrate seamlessly.

Price: Free

Price: Free for an ad-cluttered version; from $12.90 a month to remove the ads and use your own URL

This hosted software lets customers edit any part of an online community you allow them to. uses it to let registered users revise the site's database of articles or add their own.

Price: $1 to $10 per moderator (an employee overseeing the community) per month; $100 per month minimum