I would love to get people to sign up as members and to take an active role in my forum. What are the ways I can achieve this

go to other very popular forums, bogs and social network, post an article that is most wanted and add a link to your forum
advising they will get more stuff from your forum.

but before that, firstly, add articles and post, of products, contents on how-tos and everything you know is very useful info. post in it all this forum.
you can use Forum article Poster, it will automatically post your articles to many forum and drive back the links to your forum. all the same. make sure your forum is full with lots of contents so they wont run away.

Thanks a lot