What is the best and most effective way of promoting a domain you monetize with a domain parking company? I mean, how to do it without annoying your genuine visitors?

Why not make it something in which genuine visitors would be interested? It seems like you will get more word of mouth and repeat visitors by following that angle.

Yeah, unless you have no time/resources to throw at the domain, I'd put some work (and content into it) and then market it. If you're hard up for time, you could pull in RSS feeds and perhaps some tools.

Aside from that, if you plan on making a go with this domain, definitely add an email list signup (to something like aweber or mailchimp) now and start building your list.

Thanks for the advice guys. What if I didn't plan to build a website for the domain and instead, I just want to sell the domain. Do I still need a simple website (or web page) for the domain?

Maybe I'm missing something, but I don't see how the question applies. I don't promote a parked domain. I don't think anybody does. Rather, it promotes itself by appearing in a parking website.

Yet even so, why hire parking company when you can always create a page that says, "This domain is available. Call me at _____"

You don't need one but it doesn't hurt.
You could use a service like SEDO.

Well, I am talking about monetizing an unused domain name by displaying ads of a domain parking company on the domain (apart from selling the domain). You need to let internet users know about your domain to drive traffic to it, right?

You can add the link for your parked page in forum signatures, use Twitter and there are so many different ways, just Google

Check which adv. networks allow their ads to be placed on a single domain parking page and use them. You will earn more than if you park the domain anywhere with domain parking service providers.

That's a good point HostColor, thanks. Does it mean that I will have to create a single page to display the ads and host it on my own (shared) server?

You can have links to subpages linked at your homepage and can use them on shared hosting package.

You will definitely have to put in some original content, for it to be considered for good monetizing programs. Once content is set and running go for CPM advertising and get some traffic, then you can go for selling your ad space on your site.

Best of luck!

I suggest you to do backlink building