DailyFX Forum
Includes general trading discussion and forex tax advice.
http://www.learncurrencytrading.com/fxforum/

Elite Trader Forums - Currency Trading
One of the largest communities of traders online. Free.
http://www.elitetrader.com/vb/forumdisplay.php?s=&forumid=37

Forex Boards
Forum to post and discuss views and comments on various forex-related issues.
http://www.forexboards.com/

Forex Fisherman Forum
Talking about trading systems, indicators, tools, and tutorials.
http://www.fxfisherman.com/forums/

ForexForum.net
General topics, financial associations, trading platforms, forecast techniques, and news.
http://www.forexforum.net/forex-forum.php

Forex Forum at BabyPips
Forex trading discussions focused on beginner traders.
http://forums.babypips.com/

Forex Forum @ Forex Factory
Premier community of online forex traders with user-friendly forum.
http://www.forexfactory.com/forum.php

Forex-TSD
Talking about metatrader indicators, experts advisors, and automatic trading systems.
http://www.forex-tsd.com/

Fx Pimps
Forex discussion board designed to share strategies
http://www.fxpimps.com/

Fx Pit
Independent discussion forum for forex traders worldwide.
http://www.tradingintl.com/forums/index.php

FX-Review
About forex trading services, signals, blogs, trading systems.
http://www.createphpbb.com/phpbb/?mforum=fxreview

Global-view.com
Founded in 1996, these forums are geared to providing twenty-four hour a day support to foreign exchange traders of all levels of experience.
http://www.global-view.com/

GoForex.net
Questions and answers forum.
http://www.goforex.net/forum/

Gridmeister.com - Forex Grid-Trading
A german forex-community, mainly about automated grid-trading
http://www.gridmeister.com/index.php?option=com_forum&Itemid=26

Moneytec
Traders community forum with section dedicated to forex. Free
http://www.moneytec.com/forums/index.php

Oanda FXMessage
Wide discussion board opened to registered users, not necessarily clients.
http://www2.oanda.com/cgi-bin/msgboard/ultimatebb.cgi

Spreadtrade2win
Making a tax free fortune and helping others do the same.
http://www.spreadtrade2win.com/forum/viewforum.php?f=2

Trade2Win
Community website for active traders, short-term and daytraders, with live trading discussion boards.
http://www.trade2win.com/boards/forumdisplay.php?f=54