My friend has this great website/idea, how can i help him get users?

Find bloggers who are likely to like the idea. Send them press releases.

Use social bookmarking sites like delicious, digg and stumbleupon. If you use forums at all, place the url in your signature. DON’T SPAM IT though. That’s the worst way. Also, make a twitter account for the site, follow a bunch of people, and talk about the site, get people interested. Make a blog for your site, and use things like google adwords and adsense. Once you get a good number of guests coming to see the page, make sure you keep things going, and make sure you leave them coming back for more.

Is it a website or is it an idea? Ideas are cheap. Not many people are interested in ideas. People are more interested in a demonstration of the idea, as in, the final completed website, or at least a prototype with screenshots illustrating the idea. Hiring a PR person prior to having a demo is not an advisable idea.

Funny thing. I started writing something like last.fm before I knew about last.fm.

That was a real bummer.

I have a point in there somewhere. Maybe someone can find it.

The answer to your question really depends on what the idea is, who the target audience is, and how much traffic you want or can handle at start-up.

You should also research your competition to get an idea of where you fit in the marketplace, analyze your business model based on the current economic conditions, and determine how you can make money off the site and what kinds of costs you will have on a recurring basis as well as what kind of forward thinking you need to be doing if you end up with more traffic than expected. Or less.

Maybe start by telling us all about your idea.

Funny thing. I started writing something like google.com before I knew about google.com.
That was a real bummer.

Add the url to Google
Look at some tips from google
Stumble it -Good for a big spike, make sure you are ready to roll when you do this. If the site is good, that spike will never end.

Then they will be able to find you… as for growing the userbase… idk

If you don’t know who your target market is, and where they already hang out online, you have some serious research to do. Your business plan and market analysis will tell you exactly where to advertise.

And do you mean “users” of a product/service, or “visitors” to his site?