I recommend you to use twitter.com, digg.com & Xomba.com.
I always prefer Digg & Xomba (your article will be listed in Google within few minutes if you use these backlinking sites).
I highly recommend xomba, since you can even get Adsense income as well. 10% of my total adsense revenue comes from Xomba. If you do not have a Xomba account, if you like you can use my referrel link which will increase my percentage of adsense sharing http://www.xomba.com/referral/777e6a32