Where does the majority of your traffic come from? Referring sites? Search Engines? Direct visitors? Usually you can find this out from your analytical program (i.e. AwStats, Google Analytics, etc.)
Most of my visitors come from Google, with smaller percentages coming from Yahoo and MSN. Of course I get some referral traffic, but nothing compared to Google.
On vBCodex, 80% of my visitors come from referrals on other sites. 12% are from Twitter. 1% from search engines and the rest various or direct (i.e. Bookmarks/Address Bar).