There are many secret warriors about the Internet. Some have gone so far as to make their presence known, providing invaluable resources to friendly innerwalkers. Here are a few that we use regularly; if you know of a great site we've missed, please let us know!
Chimpshack: http://netherworld.chimpshack.org
Deckbuilding tips, play strategy, and fandom galore. Chimpshack also hosts an invaluable online searchable card database.
The Hub: http://www.shadowfisthub.com
Another card search site, as well as the most comprehensive list of Shadowfist decks online.
SecretHQ: http://shadowfist.webjaw.com/
A great spot for strategy and an always-controversial "unabashed review" of cards.
Denmark Shadowfist: http://www.scythe.hjem.wanadoo.dk/Shadowfist.htm
Regional info with plenty of strategy and card analysis as well.
Dave Van Domelen's Fist Page: http://www.physics.ohio-state.edu/%7Edvandom/fist.html
Home of the funny cards list, and lots of useful resources to boot.
Shadowfist Trading Yahoo! Group: http://games.groups.yahoo.com/group/ShadowfistTrading/
The online email forum for trading Shadowfist cards.
Mahasamatman: http://trade.mahasamatman.com/Shadowfist/
Another great trading site, with an excellent want/have search list.