I'd do these things:

1. Write up a press release announcing your game (check out the articles at http://www.dpdirectory.com/3newsltr.htm ). There are PR distribution services, but you can distribute a release yourself by gathering e-mail contacts for editors of magazines and websites.

2. Read up on marketing ( http://www.dexterity.com/articles ).

3. Make sure you submit your demo everywhere (e.g., have you hit all the big sites such as Tucows and download.com? The indie sites such as GameTunnel?) Learn about the PAD format ( http://www.asp-shareware.org/pad/ ) and submit your game to all the shareware sites you can find.

4. Place DOWNLOAD and BUY buttons prominently on your website.

And last, but not least:

5. Get honest feedback about your game, improve on it for a month or two, and release a sequel. The feedback should be somewhat painful but constructive. Ask enough people what they want to see more of in your game, and you should begin to see a consensus.

The iterative process in #5 is, IMO, the most important -- many indies seem to get discouraged and dump a project rather than finding out which parts to improve and improving them.