I've always been curious about the Pessoa lunging system. It is way out of my price range for a gadget that I may not actually like. I'm also not big on lunging as I want to get the physical benefits out of riding for myself as well. With four horses at varying stages of training though, it looked to be something that might help spread me around better.
I had a neck stretcher that I'd bought at Dover that was decent enough, but again, I'd been choosing to ride and not lunge when the opportunity presented itself. For my "tougher" horses (Mango and Piper), I'd bought a german martingale that only acts when they lift their head and serve as a quiet reminder to stretch down. It works great with both of them as they're rather clever.
This is the trying out of the Balance System from State Line Tack in the pictures. Piper did really well with it and I was able to adjust it to help her balance better at the canter with minimal contact. Katy didn't get much out of it and Mango was just ok. It didn't sell me on the item at this time, but as the horses get more advanced and I buy more essentials that are more important I may consider getting one just to help exercise them out.