I don't remember any domains really. They are in my favourites or I search in google and most of them appear.
For example, if you search for web directory, IT support forum, link bid in Google.co.uk, my sites appear on page 1 so visitors don't need to remember the url.
I think it also depends on the type of site. If you are selling products, then yes, an easy to remember domain name is good.
But hypens can have an advantage e.g. a site name this-is-my-site.co.uk is easy to read to the human eye compared to thisismysite.co.uk
I was reading around and most recommend that you should try to avoid more then two hyphens