The Church of the Latter Day Yukkuris (required reading for newcomers)
http://shii.org/yukkuri/

irc:
irc://irc.synirc.net/easychannel

online irc client:
http://chat.mibbit.com/?server=irc.synirc.net&channel=%23easychannel

irc program for Internet Explorer:
http://www.silverex.org/download/

google group:
http://groups.google.com/group/yufanfics
or
https://groups.google.com/forum/?fromgroups#!forum/yufanfics

google site:
http://sites.google.com/site/yukkurifanfics/

classic stories / Contains summaries for ankos :

http://yukkuri.shii.org/wiki/show?nordirect=1&title=text_stories

Yukkuri on Reddit:
http://www.reddit.com/r/yukkuri/

The 2chan yukkuri thread can be found here:
http://jun.2chan.net/51/futaba.php?mode=cat

Other yukkuri image upload sites:
http://thewaterducts.sakura.ne.jp/cgi-bin/up/upload.html
http://www6.uploader.jp/home/slowslow02/

A livedoor bbs where yukkuri stories are posted:
http://jbbs.livedoor.jp/otaku/13854/

Ancyclopedia: Japanese guide to yukkuri types, terminology, artists, and writers
http://www29.atwiki.jp/yukkurifutaba/

Yukkuri on Pixiv:
http://www.pixiv.net/search.php?s_mode=s_tag&word=%E3%82%86%E3%81%A3%E3%81%8F%E3%82%8A