If you have the time and the budget, these conferences often deliver a wealth of elearning knowledge and experience.

ASTD TechKnowledge
Year after year, this well-run conference provides high-caliber presentations on training and technology. Usually held in late January and early February, ASTD Techknowledge features workshops, presentations, and exhibitors. If you can attend only one conference on virtual learning, this is the one.

eLearning Guild Annual Gathering (spring) and DevLearn (fall)
The eLearning Guild hosts two major conferences each year with each featuring workshops, presentations, and vendor expositions. The Annual Gathering is usually held in the Eastern U.S. in the spring and DevLearn is usually held in the Western U.S. in the fall.

eLearning DevCon Conference
This conference began in 2004 and is tightly focused on the development of online training content. The conference is organized and run by Rapid Intake, a provider of elearning content software.  DevCon has been held in Oregon and Utah in July and August in the past.