The presenter at my first session recommended the book The STEM Shift for teacher leaders wanting to start a STEM program in their schools. It makes a good staff wide read as a possible option of professional development.
She also recommended contacting local colleges, technical schools, and employers in STEM fields to set up classroom visits or field strips. Many are happy to work with groups of students.
At another session, the presenter recommended Engineering by Design as a k-12 STEM curriculum. In many cases you can get free access through your local intermediate unit. The curriculum in dense enough that it could be a stand alone class, or teachers could pull individual lessons for use.
If you are looking for a free resource to evaluate your current STEM program and want some directions for the future, check out the evaluation tool at Carnegie STEM Excellence Pathway.
Finally, there there is a huge need for computer programmers. Code.org has free curriculum including the very fun Hour of Code.