Yahoo has unveiled their new web-based mail system, an overhaul 2 years in the making. 

Among the new changes:

• built in instant messaging
• real-time chat, right from within Yahoo Mail, without having to run your IM application
• send text messages directly to a cell phone, and receive texts in return
• unlimited storage space (Gmail offers 2.9GB, Hotmail 5GB)
• improved search function to search your own mail by keyword
• send attachments up to 10MB in size per message
• Drag messages to new folders
• select a group of messages at once
• right-click a message for expanded options
• new tabbed interface
• a message preview pane (just like Microsoft Outlook)

Overall it is a vast improvement, and almost immediately vaults Yahoo to the top of the web-based email marketplace.  You can sign up for a free Yahoo Mail account here.