I spammed some forums on a site 1200 alexa and got 800-1000 visitors / day for 3 months straight (then a guy reported me and the threads are gone) But i'll pm the site admin and tell him to approve my new threads.
The threads were linking to my site where i provide VALUABLE CONTENT & RESOURCES.
let's take the MMO niche, for example.
Do you know why
http://www.vretoolbar.com/articles/directories.php is seen on every single internet marketing blog / forum?
Because it's a valuable resource!
Collect the best 10 Free tools on keyword research, collect the top 10 of web 2.0 sites, web directories, article directories and other shit like that.
Also provide a free .pdf plan or something.
And open threads on 50-100 internet marketing forums. You'll be the new guru, people will optin to your list, will follow your advice, will buy things that you recommend etc.
Anyway, enough on reputation creation, Just provide quality, value and you can spam your links on high traffic sites without getting banned. =)