Ok, I know I can use a blog program like wordpress, but I would like to make reviews on all the tours in Thailand and for people to leave comments, just like a blog, but I want my own page.

Do I need a new database for this? I only have 2 and the being used by my forum and my blogs.

Surely there must be a simple way people can just comment on a page. But Spam could be a problem too yes?

A database is NOT a single use tool. One single database could hold the tables for dozens of "forums" or "blogs".

You simply give the tables a prefix to their name to make them unique.

EG:
Joomla could be prefixed with "joo"

Wordpress with "wp"

a second wordpress blog with "wp2"

and so on.

Sweet, I didn't know that.