First and foremost, you want to email your family & friends and have them do the same. After that, I suggest that you make sure to submit your site to all of the major search engines. Then you can advertise, use social sites like Subbmitt to spread the word.
Also don't forget simple things like business cards, flyers, etc. Tell everyone you meet. Buy promotional items like tshirts, hats, or bumper stickers. Use resources from the list below. There are many more than what is listed below, I tried to cover all of the major things you should be taking advantage of to spread the word. I'm sure others will chime in with their answers as well.
Search Engines
www.google.com
www.yahoo.com
www.a9.com
www.msn.com
www.gigablash.com
www.dogpile.com
www.ask.com
Social Bookmarking Sites
del.icio.us
www.stumbleupon.com
Social News Sites
www.digg.com
www.mixx.com
www.reddit.com
www.subbmitt.com
www.fark.com
RSS Feeds
www.feedburner.com
Press Releases
www.prleap.com
www.urlwire.com
www.prweb.com
www.ereleases.com
Promotional Items
www.cafepress.com
www.bizcards.com
Video Sites
www.youtube.com
Social Communities
www.twitter.com
www.facebook.com
www.myspace.com
www.linkedin.com
www.flickr.com
www.fark.com
www.sharethis.com
Banner Ads
www.traffiq.com
adwords.google.com
Directories
www.wikipedia.com
www.nypl.org/links
www.technorati.com
www.dmoz.org
Webmaster Tools
www.google.com/webmasters/
http://siteexplorer.search.yahoo.com/
http://www.seomoz.org/tools
http://www.spyfu.com/
Targeted Ads
www.revisitors.com
Link Exchanges
http://www.adgridwork.com/
Viral Marketing
www.bzzagent.com
