A little idea I had just now: What about adding an email checking functionality to the Menu?
Nothing fance, just checking one or more POP3/IMAP accounts in the background every x minutes and giving some optical feedback if new mail arrives (animated trayicon, litte popup).
That would eleminate the need to have my own email program or a separate checker running all the time.
A click on a popup (if you don't go for the animated icon) could either start a portable email program or open a webmailer page in a browser (ideally a portable one, ideally a different one depending on the account checked).
I know that loading the menu with to much functionality is not a good idea, but I always want to know if new mail arrives... just think about it.