http://www.writersonlineworkshops.com/

Holly Lisle has online workshops

http://hollylisle.com/honing-your-talent-a-workshop/

Critique Circle isn't a workshop, but you can post your work and get it critiqued. The best way to get better is to write and see what other writer's think of it.

http://www.critiquecircle.com

I'll check it out.

http://www.catalog.dcs.wisc.edu/

Just click on the catalog and select creative writing.

You get a year to complete most classes and they aren't too pricey. You can even get college credit if you want.

I've always had a good experience at their conferences and workshops. Your mileage may vary.