I would say, if they are legitimate businesses, then the Fourth Circle, but because most are scammers too, the Eighth Circle would probably be the place for them to go.
First Circle (Limbo)
Second Circle (Lust)
Third Circle (Gluttony)
Fourth Circle (Avarice and Prodigality)
Fifth Circle (Wrath and Sullenness)
Sixth Circle (Heresy)
Seventh Circle (Violence)
Eighth Circle (Fraud)
Ninth Circle (Betrayal)
8th circle IMO.
And you shoulda made this into a poll 
Eighth definately.
Personally I find it interested that this spammer is clearly a sign of the coming Shoe Event Horizon.
Their souls should be torn asunder, so that they can occupy several Circles at once.
7th - Violence - against the peaceful community of a board
4th - Avarice - to seek profit by intruding so
9th - Betrayal - after promising to abide by the TOU, and then... that.
So much lose.
I agree with the 8th, several of the Bolgias are pretty spot on: 1 (sexual pandering), 2 (flatters, propagandists), 7 (thieves), 8 (dishonest advisers), 10 (liars).
None of the above of course, they have their very own special place right in the center of all those circles.
9th circle - betrayers, obviously, of the TOU.
Is there any way a moderator can delete the spam?
Well, mimi's stuff has been there for 3 days which is not a good sign. The longer it stays, the better impact on google it has and the more likely we'll get more. 
Well for spamers I think the chinese hells refered to in "big trouble and little china" would apply ... heel of the upside down sinners and the hell of being flayed alive.
Hm. I guess I'll have to go with 4th, though I really think that they belong in a special place where demons work out thier frustrations after a long day at work...
Third circle, following the internet revision:
I'm not sure of the source, but one version of the final diagram is here:
