Thanks for posting this thread, I'm seeing some really great ideas. Here is what I've used so far on my 26.75 OTG, similar to a lot of others.
I got a used 2" X 16" pizza pan from my local restaurant supply place cheap ($3.00). It works centered on the grate with a complete ring of charcoal but so far I've only used it as pictured, a 3-1/2 cook and had about 1/3 of the charcoal left over. I do like the CI ideas.
Edit-PS: I'll also just use a couple firebricks to split the grill surface when I want to smoke indirect for a while then do a direct reverse rear (chicken,steaks, tri-tip, etc.). I'll be adding Bludawg's technique for air control to this in the future!