If no one is interested you should wonder why. Did you target the wrong people? Are there better sites covering the same topics?
There's nothing special in advertising slash sites...
For my own slash sites: I usually write a site for a specific goal. If that goal requires the use of slash I use slash, else something else. Given that I first try to find my readers and then implement the site it's not really difficult to start with some friends and interested users.
Once you go live you can always send announcements to web news sites, news groups, mailing list, advertise in guest books, pay for ads. Just one rule: don't spend your time and money on people who don't want to read your site anyway.
-- symlink.ch [symlink.ch]: YAGSS - yet another German slash si
Topic is important as well. It seems to help if your site has a specific focus (and it's well documented in the FAQ or some other "policy" place), something for the users to associate your site with. You don't necessarily want too narrow a focus, but trying to be everything to everyone will drive you insane (and maybe drive contributors away).
I've also found that it takes a while to get a good viewership. I did a lot of posting for me, myself and I (and a few friends) before people started to contribute. I assume many people like to sniff around and check the place out before feeling comfortable enough to post. I guess the best advice is to not be easily discouraged.
Well, these are just tidbits from my (brief) experience. I've only had my slash site up for a few months, so I'm still relatively new to all this... ;)
-- Kill-HUP.com [kill-hup.com], proudly running Slash since 1/28/2002.
meta NAME="robots" content="INDEX,FOLLOW"
meta NAME="revisit-after" content="1 days"
Combine this with a Robots text to exclude the .pl pages.
Adjust the "revisit after" parameter so the the search engines will visit you regularly to index new content.
This way you start showing up in search engines when people search for the things you cover.
2) Include a link your site in you signature when you post on other web pages, in your email messages
3) Link to stories on your site when relevent to your comments in other forums.
4) CnetRadio.com has a radio show feature on Fridays 11am called Free Plug fridays. phone up on an 800 line. have your act together and have a pretty cool angle to promote it on the radio in San Jose, Boston, other cities, and on the Internet for free.