Sorry I'm not aware of any good internet resources, but here is the quick rundown of general surgery national meetings that I pay attention to. Most regional meetings (Pacific Coast, Southeastern, Southwestern, Central, Midwest, and New England) also meet in the spring. Sorry, I don't feel like checking them up right now, but google should find them for you.
I defined Spring as Feb-May; If you want other dates, ask.
Date Society (location)
Feb 7-10 Association for academic surgery + Society of university Surgeons joint meeting (San Diego)
Mar 9-12 American Hepatopancreatobiliary Association (Miami)
Mar 23-26 Society of Surgical Oncology (San Diego)
Apr 5-9 american Society of Breast Surgeons (Baltimore)
Apr 23-26 American College of Surgeons Spring Meeting (Dallas)
Apr 26-29 Socity of American GI Endoscopic Surgeons (SAGES) (Dallas)
Apr 29-May3 American Association for Thoracic Surgery (Philadelphia)
May 7-9 American Association of Endocrine Surgeons (NYC)
May 20-25 Digestive Diseases Week (Los Angeles)