My local chapter co-sponsors on-track events at Road America and the local drag strip, spirited drives through the countryside, and meet'n'greet events & shows throughout the summer. We also get a discount (albeit a small one) at the sponsor dealership.
I actually let my membership lapse, and no one seemed to care here, either. Its not like they take computerized attendance with the national SVTOA rolls or anything. However, our local chapter coordinator has to submit forms to SVTOA national every so often with signatures of local members so they can maintain their status as a chapter. I'm assuming if you aren't paying dues your signature won't count.