GMail has to be my favourite webmail ever! One big bonus it the constant improvement. Not only does Gmail grow in storage capacity but Google adds applications and tweaks generally on a regular basis.
And now, Google mail lets you include gadgets on the left-hand side. These gadgets can be enabled within Gmail under the Settings tab. Provided are two gadgets - Google Calendar and Google Docs, showing upcoming events and recent documents.
If you are working a lot with Google Documents and/or Calendar, this is certainly worth it.
