When building a website like a dating or a forum or something of that type should one consider using a design pattern? could anyone here tell me what are the advantages to using them in context with the above website types.
Thanks
James
Design patterns cannot be dealt with except individually.
Best pick one pattern, front controller/MVC etc then choose to discuss that case by case. There is enough topic on each one to fill a thread. Some people like them as they are seemed to be a form of global panacea and others under value them because they are not the global panacea they allowed themselves to be fooled into believing they were.
To understand design patterns then OOP must first be understood beyond inheritance and without that it can just denigrate into a mass argument about the subtleties of OOP. It just gets messy when treated as a global concept, I would equally argue with those who blindly over favour as those who blindly under favour as both are equally flawed.
Dating site or forum, that domain info is not important. It is just about building a stateless beast that takes request information and processes it call by call, like all web things. Complexity is still driven by client desire, and that is very hard to premeditate like most human desire.
Good software design needs to be covered case by case and refined case by case. No exact answer can be given to you as no exact answer exists. Patterns are about OOP, and I have heard arguments that patterns are just a solution to OOP’s problems so the word pattern entices argument even on that level.
There are a lot of design patterns and they cover many diverse areas of software construction to cover the many diverse flaws. I just don’t want things to degenerate again as I find it distressing, there are enough excellant seperate discussions held within the question you have given so it is best not to cheapen them with one thread. It will be far more productive 
It’s difficult to explain to someone who ask this kind of questions. Design Patterns are general solutions to general problems. You have something in mind, but you didn’t encountered yet a problem you should solve in your code. It’s also difficult to explain what and how to use design patterns in a simple thread.
Like pgb101 said you will probably have to read about front controller/MVC. This is probably you need to implements for a web application. Most probably you will have to read about factory pattern, singleton and other patterns, because they are widely used.
IMHO the understanding of design patterns doesn’t come solely from reading, but from practicing, coding, making mistakes and understanding what you did wrong. This is why asking on a forum might be a starting point but you need to do more for it.