I found oat fiber - it is almost pure fiber, and can be added to many things.
I have added it to Bisquick heartsmart mix and yogurt. DH made muffins and put some in.
It has only 5 calories per ounce and a whopping 26 grams of fiber. I mix in several grams to up the fiber content on food.
Honeyville Oat Fiber


Thanks for the link -- I just ordered some. DH has IBS and fiber is the cornerstone of IBS treatment, plus this is soluble fiber which is gentler on the gut than insoluble. Fiber is something I always can use more of, too -- it really helps fill me up on fewer calories. 