The homepage of the American Association for the Advancement of Science offers a variety of webinars on all kinds of science-related topics:

http://webinar.sciencemag.org/

You can also sign up for Career Webinars:

http://webinar.sciencemag.org/all-webinars/career

These webinars intend to offer you unique perspectives on topics that directly impact your scientific career and aim to introduce you to new facets and arenas of scientific endeavor that you might not come across in your day-to-day work.

The Career Webinars are free of charge.