As for non-Google email, my work uses Exchange – and I can’t reach an secure port for that without firing up the work VPN, so usually I use the shockingly clunky webmail alternative anyway – so its not like I am losing out on any functionality. I have a .mac address which truth be told doesn’t get used that much – and Gmail can suck in pop-based email into it’s own accounts anyway. It can be used with an unlimited number of Gmail accounts.

If you are a Gmail user on a Mac, I’d definitely recommend having a look at Mailplane.  It’s a nice way to get the Gmail-native way of handling email (which generally I love)  onto the Mac. I think its needs some improvement, such as integration into Apple’s iCal, and perhaps, if possible, the abstraction of some of the Gmail interface elements (such as gmail’s list of labels) out into native interface widgets.