There are many ways you can share stuff with your friends using the new Messenger button on the Yahoo! Toolbar:
Messenger Status
To set a web page as your status in Yahoo! Messenger, please do the following:
Now all your friends can see that URL next to your name in their Messenger Contact list and select it to see what you're seeing.
IM a page
You can IM a web page to someone on your Messenger Contact list by doing the following:
IM selected text
You can send any text on a web page using Smart Tools:
The Messenger button requires Yahoo! Toolbar 6.2 for Internet Explorer or newer, and Yahoo! Messenger 7.0 or newer. To check the version of your toolbar, select "About Yahoo! Toolbar" from the Pencil menu. To check the version of your Yahoo! Messenger client, select "About Yahoo! Messenger" from the Help menu.
If you have Yahoo! Toolbar 6.2 for Internet Explorer and Yahoo! Messenger installed, but don't have the Messenger button on your toolbar, you can add it to your Yahoo! Toolbar now (this requires sign-in).