Did you add them to google and yahoo manually? If you did then consider:1) Adding a link to your blogs to yahoo.answers (e.g. by editing your question). Just use common sense and do not spam2) Maybe concentrate on one blog? This way you could use it as your sig when posting on forums3) Adding your site to linkreferral also helps (at least from my experience).4) Most important! CONTENT! If you have anything valuable to say, google and yahoo will find you

Be patient and you will see the results. Remember that it takes time for a crawler to visit your site so do not expect immediate results.
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