There's a tremendous amount of free resources and software on the web, from informational websites, to educational podcasts, learning simulations, assessments, open source software, etc. The first step you would need to do is to identify exactly what you need (content area, grade level, instructional application, etc), then start your search from there. That should help you focus your question and find what is available that will be useful to you.
Another thing to look into is a PLN (professional learning network) These are great places to ask these kind of questions. I am very hooked on Plurk right now (much like Twitter, but better) Whenever I have a question like this one, I plurk about it and get tons of answers.