In my opinion, judgment-based workshops (conducted either in person or on the net) are not very useful. The most critical thing in any art is the ability to self-edit: to compare your stuff to other stuff and see the reality in your work.
Fact-based workshops (how to use lighting equipment, "Compositing in Photoshop," "Making a fine print," etc.) can be very useful. Hang-out workshops (hanging out with a group of people who have the same interests and who exchange ideas on technique, etc. and simply share the experience) can also be fun and even inspirational.
Judgment workshops, however, above the most basic level, tend to involve very strong ideas about art, that differ from one brilliant photographer to the next. One guy looks at a John Sexton photograph of aspens and sees a brilliant work of art, the next guy sees a cliche. Who's right?
One of the hardest things about photography or any other art form is that you have to do 99% of the hard work on your own...