To kill the spam you must kill the benefactor (the advertiser) why not post heavy fines and penalties on these guy. I get junk every day from legitimate mortgage, manufacturing, medical, etc… HELLO these are the guys paying to send the spam. Kind of like the king pins in the Drug industry placing their name and address label on every drug they sell. They broadcast themselves every day. Why don’t they get stung. In the event we signed up for their junk make them prove it. Am I missing something here because it seems like a no brainier to me. Sign in Visa,MC,AMEX,DISCOVER,PAYPAL and all other big time payment systems into the legislation and require them to firewall any payments made to blacklisted offenders. No sales stops the advertising payments real fast. That’s how you kill the spam business short of shutting down the internet all together. Want to know how to kill the drug industry - poison the drugs and let them go to the streets only the biggest junky of junkies will continue to roll the dice. Leave the pot alone because I kinda like that one sometimes - helps kill the frustration of all the spam I need to filter through every other day.
hotcapcha is a little subjective - I wasn’t sure there was a third hot one 
I have an onlines savings account that has a terrible system though. You have to put in about twenty secret questions. I’ll never remember all the answers, or I’ll have changed my mind, or something by the time I have to access it again.
As well as putting together multi-factor authentication for stuff like online banking, there also needs to be a culture-change. Governments need to get tough and prosecute and also religions/moralists/parents/whoever need to educate the next generation that it is wrong to steal.
When making a comment on the Wolfram or MathWorld site, they ask you: 3 + 4 = ?
The math is even in plain text on the page.
Not sure what their success rate is, but it is probably pretty good. For email providers, this would obviously be overrun quickly. Word problems would be even better. They could even be simple and take a lot of different forms: “What is 4 from seven?”, “Jill gives Johnny two apples plus three oranges. How many apples does Johnny have?”
I think it’s time to add some inteligence in the process, what about ‘questions’ like these:
a banana cost $1. three bananas will cost $_____
I had a $3 discount on a $15 product. I paid $____
and the text could come as a standard captcha.
( I am Brazilian, so my writing might have some mistakes ).
A surprising number of the suggestions above are culturally dependent. For example:
Not everyone has a Social Security Number. In New Zealand for example, the is no universal personal identifier (and long may that freedom continue).
Not everyone has a drivers license. I was 42 before I felt the need to get one.
Not everyone will recognise an athlete dribbling a round ball as related to the word “basket”, as http://gs264.sp.cs.cmu.edu/cgi-bin/esp-pix just asked me.
Any trivia questions (no matter how simple) will be foreign to some people. (“What’s the second world war?” asks someone in Chad.)
Spam is a tax we pay for having email. Use spam filters - all you can.
ISPs should have better spam filters than most do: Gmail does well. Learn not to let spam annoy you.