I've talked alot about all the content you are going to need to create in order to make a search engine friendly website but what about users generated some content?
There are plenty of ways to do this but they are not nearly as straightforward as most people imagine.
Undoubtedly one of the best ways to have lots of text, and original text, added to your website is to put a forum on it. Users can discuss things there which makes for lots of original text and often very useful text that others will link to.However forums can have disasterous and unexpected side effects:
Forums also leave you in little control of what keywords will start to dominate the pages. If you sell bicycles but your forum becomes better known as a place to swap tips on repairs then your website will become better and better known for 'how to repair a bike' and less and less known for 'bicycles for sale'.
The upshot is that forums are not generally recommended for SEO unless your entire reason for being is to run a forum at your own expense.
Really this is a similar situation to a forum and once again there is a great deal of administration to do here, often unpaid.
Without proper promotion they look ghostly and empty but in any circumstances you will battle endless spammers (or even spam robots) trying to post links to whatever they are currently spamming.
Reviews are a little easier to moderate if you limit access to the visitors of your website who have actually purchased something. If you leave it wide open expect to do battle with spammers!
The idea of getting other people to add valuable content to your website for free is highly attractive however the reality is that it rarely works. Instead of fighting spammers continuously trying to hijack whatever resource you have made available you would be far better off spending your time on your own content.
I'm Tim Hill, a Search Engine Optimisation and Online Marketing specialist. I created this site to help others understand that SEO is not a mysterious black art!.
If your a newbie try the Getting Started in SEO page, otherwise feel free to dig around and learn more.