Raise your (virtual) hand if you hate spam. ME!!! We can all agree that spam is a waste of time, effort and resources. Unfortunately for all of us, it’s here to stay. There are, however, a few simple things that we can do to help control and manage the amount of spam sent our direction.
Enable Junk Mail Filtering
Just about every modern-day email client (or service) will have built-in spam filtering. You may want to look at enabling this (if you haven’t already), but keep in mind that there are no perfect filtering systems/services. They will either filter too much (including valid email), or not enough (letting some slip through the cracks). Regardless, it's a great way to filter at least most of the spam you receive. This is a good FIRST step.
Watch Where you Click
For the spam that does make it to your Inbox, they usually have the obligatory "Click here to be removed from this list" link in small letters at the bottom. Don't be fooled by this. By clicking that link, you confirm with the sender that you do actually exist, and will therefor receive more spam. My suggestion... just delete the email and add it to your email client's "Junk sender" list.
I got to trade shows fairly often. As part of the registration process, I am always required to use my email address. Not only is this used by the organization to communicate with you about the event, but they will then circulate that around to the various vendors. As a result... spam! Rather than using your very own email address (which you really want to change very infrequently), sign up for a free Gmail account and think of it as a disposable account. For example, if I am going to attend WWDC 2013, I will create a new Gmail account called "email@example.com" (the "ka" are my initials, which will make it easier to guarantee that I can actually get the address). I will certainly use the address during the conference (and even for a week or two after for follow-up), but after that... I forget that it ever existed.
None of these methods will 100% rid you of spam, but working together, I bet you can cut out a lot of waste. That's my story, and I'm sticking to it.