We do the obstacles too as mentioned a few responses back. It's fun to practice and fun to come up with new ideas. We have the boardwalk idea, carwash, tires set up like military courses do when they run solders through, yard spinners to go past, tarps to get creative with... More ideas we don't have set up yet is a teeter totter, water feature of some type, I've seen pool noodles used in some creative ways.
I'm a big trail rider, so the obstacles just help my horse be so much more level headed out on the trail. :)