Well after creating your own blog or website you may want others (your friends) to know about it. But you cannot nag everyone by telling that you have a blog. An easy and a great way to do it, is to include the blog in your email signature.
An email signature is like a visiting card. The people who receive your email will also receive the URL of your blog. Many email services like Google, yahoo support the inclusion of signatures with the emails that you send to others. Your signature will notify the reader of the email that you seem to have a blog and might check it out and may be he will like it.
In Google (Gmail) you can set the signature by going to settings ------> general----->>
(appended at the end of all outgoing messages)
Just type in your blog URL in the text box provided and then save your settings. Now your blog URL will be appended at the end of all the out going emails.
Similarly you can also add your signatures in your yahoo id as well.
Goto options> mail>signature and you can add the HTML tag that links to your blog.