Here's what I did just to experiment.
I copied the Sender & Subject lines from the Gmail I know is Spam.
I posted them to my tribe blog.
I fed the link to my blog entry to
www.searchenginepromotionhelp.com/m...hp

This sorted and ranked the top words and phrases.
The 3 word phrase seems to summarize the words the best.
Then I set up filters in Gmail

"nethugs newsletter january" OR "gift card claim" OR "read see email" OR "card claim 250" OR "starbucks gift card" OR "meet christian singles" OR "250 starbucks gift" OR "erase wrinkles botox" OR "favorites win favorite" OR "victoria secret gift" OR "wrinkles botox erase" OR "win favorite things" OR "mabry highway pmb" OR "highway pmb 438" OR "gift card type" OR "5692365 gift card" OR "confirmation 5692365 gift" OR "card confirmation 5692365" OR "gift card startbucks" OR "card startbucks gift" OR "startbucks gift card" OR "gift card confirmation" OR "13176 dale mabry" OR "dale mabry highway" OR "claim 250 ikea" OR "look years younger" OR "250 ikea gift" OR "gift card complimentary" OR "trial look years" OR "ikea gift card" OR "save 70 discount" OR "70 discount fragrances" OR "biggest loser club" OR "gift card read" OR "bowflex extreme 2" OR "newsletter nethugs newsletter" OR "38 health insurance" OR "claim 250 starbucks" OR "card read see" OR "250 starbucks cards" OR "playoffs 500 beer"

"cardsharks complientary 500" OR "sleep apnea control" OR "bottom 1em blogentry" OR "snoring sleep apnea" OR "complimentary 500 poker" OR "500 poker table" OR "poker table worth" OR "table poker table" OR "poker table poker" OR "effective snoring sleep" OR "professional effective snoring" OR "botox erase wrinkles" OR "1em blogentry divblogphoto" OR "250 abercrombie fitch" OR "soringcures fda approved" OR "fda approved snoring" OR "control professional effective" OR "snoring control professional" OR "approved snoring control" OR "table worth 500" OR "worth 500 email" OR "football playoffs 500" OR "kick football playoffs" OR "beer kick football" OR "perfumecom save 70" OR "500 beer bucks" OR "tue february 14" OR "2006 entertainment book" OR "500 beer kick" OR "vote 500 beer" OR "78192 3152886 bbs" OR "light beer survey" OR "beer survey vote" OR "survey vote 500" OR "brands perfumecom save" OR "offerconfirmation 06m l774tar" OR "gentleman magazine prefer" OR "guys gentleman magazine" OR "prizes regis kelly"

"protect family financial" OR "mind protect family" OR "peace mind protect" OR "oprah favorite things" OR "abercrombie fitch gift" OR "see offer description" OR "offer description subjects" OR "description subjects playboy" OR "favorite things win" OR "win oprah favorite" OR "york city philadelphia" OR "things win oprah" OR "family financial crisis" OR "financial crisis accuquote" OR "250 victoria secret" OR "1000 charge ringtones" OR "hey guys gentleman" OR "strength hundreds life" OR "3 pack shirts" OR "claim 250 victoria" OR "nethugscom newsletter nethugs" OR "limited time offer" OR "claim motorola razr" OR "lonely meet christian" OR "sears gift card" OR "compare price features" OR "accuquote compare price" OR "crisis accuquote compare" OR "price features financial" OR "features financial strength" OR "100000 sears gift" OR "christian singles wwwnethugs" OR "financial strength hundreds" OR "subjects playboy penthouse" OR "penny giftcard offer" OR "jc penny giftcard" OR "perfumecom perfect valentine"

"day delivery satisfaction" OR "flowers starting 2999" OR "bargains name brands" OR "great bargains name" OR "day gifts great" OR "just corner valentine" OR "giftcard offer confirmation" OR "day flowers starting" OR "penthouse vote favorite" OR "confirmation 643e 5p74y" OR "participation read see" OR "offer complimentary sets" OR "hanes 3 pack" OR "sets hanes 3"

Wow, really? I hardly get any spam on my gmail that doesnt get caught by the spam filter...it's FAR better than the filter on my yahoo or hotmail accounts (which these days I use specifically as spamtrap/sacrificial-lamb accounts.
But then, I use gmail as my primary account now, and login multiple times a day.

Considering how I have used my three webmail addresses in the past (hotmail, yahoo and gmail, in chronological order), I think much has to do with how often I posted my email address somewhere on the web. I try not to post it at all publicly, but some sites will only allow you to register and will always post your email address without using e.g. yourname[at]gmail.com as tribe does.
I took a yahoo address after my hotmail was being overwhelmed by spam. I only used that yahoo address for friends and never gave it out to a stranger or posted it on a website. And I have never gotten one piece of spam.
I have been using gmail for both friends and registration, and the spam has been building up gradually, most of it in the spam box, but I am getting up to 10 a day. I hope this does not repeat the hotmail experience.