3 bonus resources- affluent population, fine jewelry, and steel. Maybe more depending on the wildcards.
You can sign up if you have one or two of the LISTED resources with no resources doubled in the circle. You cannot sign up if you have two wildcards. For those who don't know a trade circle is 6 nations that all trade with each other for stability, bonus resources, and team bonuses. You'll need a harbor and to be on white team when the trading starts.
Gold- [url=http://www.cybernations.net/nation_drill_display.asp?Nation_ID=364632]Twink[/url]
Silver- [url=http://www.cybernations.net/nation_drill_display.asp?Nation_ID=364632]Twink[/url]
Gems-
Coal- [url=http://www.cybernations.net/nation_drill_display.asp?Nation_ID=417589]Eiros[/url]
Wine-
Furs- [url="http://www.cybernations.net/nation_drill_display.asp?Nation_ID=439084"]Playaman[/url]
Fish-
Iron- [url=http://www.cybernations.net/nation_drill_display.asp?Nation_ID=419509]Ultraboredom[/url]
(Wildcard)Water-[url=http://www.cybernations.net/nation_drill_display.asp?Nation_ID=419509]Ultraboredom[/url]
(Wildcard)Oil- [url=http://www.cybernations.net/nation_drill_display.asp?Nation_ID=417589]Eiros[/url]
(Wildcard)Aluminum- [url="http://www.cybernations.net/nation_drill_display.asp?Nation_ID=439084"]Playaman[/url]
Uranium-