I use gmail mostly as a "spam" account; any website I sign up for (even SF) I give that address. The beauty is that the spam filter is so good that I rarely get anything via POP3 (another reason) that isn't meant for me. Gmail helps to keep my emails separated in my Mail program in terms of "business" and "pleasure."
I wish I had done that years ago with my hotmail account. Still, it's catching most of the crap these days and i've gotten myself unsubscribd from several annoying lists.
Imagine being Bill Gates or the president though. I think i remember reading once that he gets something like a million emails a day and has an entire department devoted to eliminating the junk and sending him the relevant stuff (only 200 emails lol).