General Information

The American College of Gastroenterology publishes an email newsletter with useful and interesting information for IBS and IBD sufferers.  Here is a link to sign up for their excellent newsletter:

https://www.smartbrief.com/dhsb/index.jsp

The same group has posted a glossary of GI-related terms, which can come in handy if, say, you've forgotten the definition of Percutaneous transhepatic cholangiography.  They also cover all the more common terms...

http://patients.gi.org/topics/understanding-your-gi-tract/

Here is their section on abdominal pain syndrome: http://patients.gi.org/topics/abdominal-pain/

And one on IBS: http://patients.gi.org/topics/irritable-bowel-syndrome/

Chronic functional abdominal pain, which is generally considered distinct from IBS, is described here in a Wikipedia article and here in an abstract from the medical journal Gastroenterology.

Groups and Organizations

The IBS Self Help and Support Group has over 50,000 members  http://www.ibsgroup.org

LinkedIn has several IBD groups, "IBD - Crohn's Disease & Ulcerative Colitis - CCF" the "IBD Research Foundation" and "Crohn's, Colitis & Digestive Disease Support Network".  There isn't much on LinkedIn for IBS however.

http://www.dailystrength.org/c/Irritable-Bowel-Syndrome-IBS/support-group

DailyStrength has an IBS support group here

IBS Network, formerly "The Gut Trust", is a British group offering support for a fee.  Be careful, they spell some words funny.