I'll second Yahoo... it's not perfect, but it works well enough (no POP3 though, you'll have to use the web interface unless you upgrade your account, which no longer makes it free).
The bottom line about spam is that if you don't give it out, don't post it publicly, you won't get hardly any spam (I've yet to get any real spam in my inbox in a long, long time).
Follow the following tips and it'll help keep your spam down:
1) Don't register the e-mail with most web sites... all those joke-a-day, personality stuff, etc... they all tend to sell off your e-mail for spammers. If you're going to do that, pick a bad service for spam (such as Hotmail... gonna get PMs on that one
) and use that address.... it's literally an address you let spammers have.
2) Don't post your e-mail address anywhere public. This includes Newsgroups and Web pages. There are a couple of ways to get around this. I've noticed that e-mail addresses listed in Yahoo News articles are usually done something like: madphilb-at-yahoo.com. It's up to the user if they want to e-mail to copy - paste - edit. The author of RPG World comic I noticed uses an image with his e-mail address in it, so it can't be read by spambots (but people can read it).
3) Use Blind Carbon Copies for sending out something to a bunch of friends, and encourage everyone to do the same. Send the message to yourself, then BCC all your friends... while this doens't specifically help you, if everyone started doing this then it would keep those e-mails with 100 addresses forwarded every time from ending up in the hands of a spammer (or in the grips of a spambot) and will help keep your e-mail private.
4) Similar to #1, don't give out your e-mail to just anyone outside of the internet. Many of the bigger companies (EB Games, Borders, etc.) might send you stuff, but they won't be selling off your e-mail and you can get yourself off their lists if they send you stuff, other companies might not be so friendly about keeping your info private.
Yahoo does have spam filtering, but the only thing it's caught for me has been private messages sent to me from people... somehow they got listed as a spammer (or the message looked that way).... check your spam folder before deleting... I will say this though, and old account that I had that had been registered somewhere (and got me on at least one spam list) had it's spam filtered pretty good... and the one series of messages that kept comming to the inbox I could filter on the domain name (dumb spammers).
Hope this helps.
. This is very fustrating and quite frankly, I'm sick and tired of it, plus I would rather read my own e-mails before my parents do. 
So, can someone recommend some free e-mails that have very few junk mail and are safe and secure, and have all those other necessary features that e-mails ought to have (like good security)? Thanks! 
