I have several GMail accounts that I use for various Yahoogroups email lists. That works really well because that mail isn't pouring into my regular email account inbox and I can also easily archive them for later reference if I want. I let 'em pile up unread for a while, too, when I'm really busy and it doesn't make any difference, unlike with my regular email account.
Most of my accounts are at around 10-15% of their total capacity, I think....
OTB