I hate blog spamming and I will fight it with all my forces... 
My first countermeasure against the last trackbacks spamming (and I hope the last but I know that spam has no limits) was taken from an idea by Chrissy Le Mair: a SQL Trigger that acts as anti-referral spam filter. This is the quickest remedy that can interact well with my SQL antispam filter that I have from a long time.
Firstly, I've totally cleaned the spam referrals urls with a simple SQL script launched via Enterprise Manager. The .Text tables that must be cleaned are the blog_URLs and blog_Referrals tables and the cleaning operation can be done with a simple script that do something like this:
delete from blog_URLs where URL like '%poker%'
........... the deletion is repeated for every word I've on my Spam Blacklist .......
delete from blog_Referrals where UrlID not in (select UrlID from blog_URLs)
After that, I've created 2 SQL Triggers for the table blog_Referrals, one for INSERT operations and one for UPDATE (I'm not sure if updates will never occours but this is for prevention).
The Triggers comes from Chrissy's idea (I've added other little operations but they're not important):
Create TRIGGER tgRefSpamCleanU ON dbo.blog_Referrals INSTEAD OF UPDATE AS
Declare @BannedWordsCount int
Declare @URL varchar(255)
Set @URL = (select URL from updated u JOIN blog_URLs b on u.URLID = b.URLID where u.URLid = (select URLid from updated))
Set @BannedWordsCount = (select count(*) from MySpamBlackList where charindex(SpamWord,@URL) > 0)
IF @BannedWordsCount = 0
BEGIN
update blog_referrals set lastUpdated = getdate(), count=count+1
END
go
Create TRIGGER tgRefSpamClean ON dbo.blog_Referrals INSTEAD OF INSERT AS
Declare @BannedWordsCount int
Declare @URL varchar(255)
Set @URL = (select URL from inserted i JOIN blog_URLs b on i.URLID = b.URLID where i.URLid = (select URLid from inserted))
Set @BannedWordsCount = (select count(*) from MySpamBlackList where charindex(SpamWord,@URL) > 0)
IF @BannedWordsCount = 0
BEGIN
INSERT INTO [blog].[dbo].[blog_Referrals]([EntryID], [BlogID], [UrlID], [Count], [LastUpdated])
(SELECT [EntryID], [BlogID], [UrlID], [Count], [LastUpdated] FROM inserted)
END
ELSE
BEGIN
DELETE FROM blog_URLs where URL = @URL
END
This is the end... I hope that the last trackbacks spamming is finished!