this is a list of dofollow forums which allow signature from the first post..
CashFindForum - HYIP, Forex and other online investments related discussion board.
Making iMoney.com - HYIP Forum for Making Money Online
http://www.mlmstuff.com/
Webmaster Forum
http://www.hotwebdesigntalk.com/
Technology, Web & Business Forum - Powered by vBulletin
SEnuke XCr SEO Software - The World's First Crowdsourced Link Building System
Graphic Design Forum - A Platform for Graphic Designers
Seobetter.com - Index page
DreamTeamMoney Internet Marketing Forum | Webmaster, HYIP, Forex, Network Marketing, E-Currency, Money Making Forum
Site Owners Forums - Webmaster Forums
Internet Marketing Forums
Helping Webmasters - Webmaster Forum, Website Support and T35 Hosting Support - Index
if you have some more forums please share with us too.