One Problem Google Can't Solve: Spam
I get a fair amount of email -- on average between 1,000 to 2,500 emails a day. Most, as you might expect, are spam. (Not fan mail, alas.) As a result of this figure, and of years following the spam industry both as a journalist and as a vexed end user, I've become well-versed with a number of the popular spam-fighting tools out there.
I'm particularly fond of tools that leverage the so-called "wisdom of crowds" to help combat spam: services that judge a message's likelihood of being spam based on the number of recipients who have marked it as such. These approaches have been commercially available for perhaps a decade, and have often been integrated with other antispam approaches (checksum, Baysian -- still my favorite, and so on) at either the client or server level. Many ISPs integrate some form of these kinds of solutions at the server level without end users even knowing.
Not that it makes much difference: Most of us who have been on the Internet for some time knows that inevitably, the spam will find its way into your inbox.