This is a great way to share the friends you have in common with someone who’s new to Messenger.

Click Actions, and click Send My Messenger List.

A dialog box opens where you can specify one or more people to receive your Messenger list. Click the "My Contacts" tab to select them from your Messenger List, or click the "Other Contacts" tab and enter their Yahoo! ID, Windows Live ID, or email address.

Click Next. This displays your Messenger List with a checkbox next to each name so you can select which contacts to send. By default, those receiving your contacts will also see the Yahoo! IDs and names entered in your details for these contacts. Clear the checkbox if you wish the contacts to be sent without these names.