This ease of recollection factor is important generally, but it is crucial when it comes to getting word of mouth interest in a website. And that's still definitely worth having, even though people tend to forget it.
For this reason it's always preferable to have a domain name that's fairly short. So two words is good. And three can be fine if each of them isn't too long.
I also think it helps a lot if the title you give to the whole website is an exact match with the domain name -- or at least very close to it. It also helps if it's a "dot com", because that's still the one that most people automatically think of.
And you should try not to use dashes in it if possible. If you are trying to tell someone what it is, these make it sound very awkward. And people always forget where they go, anyway. (I know there is a school of thought that says dashes can be useful for clarification in some cases where words other than those intended can be perceived. By strongly separating them, dashes make Google's job easier. But such cases are rare. And I think the search engine is more than smart enough to figure out what they are now anyway since it will factor in the website's overall content.)
If you do these things you don't even have to meticulously describe the whole domain name when you or other people verbally promote your website. You just say it is called "My Own Site". If they want to have a look they'll string those words together and usually put the "dot com" on the end and know what it is. But even if they don't they'll just search for those words and your website will tend to come up at the top of the results.