I add ground flax seed to my omelettes and and other recipies I can think of to get some fibre but of course there are carbs to be careful of in flax as well.
I just went to my Fitday for PC program and did a search for foods High in fibre per unit of carb. Some of the things I noticed are that celery and cabbage are almost equal in carbs and fibre so if you can add these to meals it should help. I make a slow cooker meal that includes stewing beef, small amounts of carrots, onions and celery. Turnips and spinach also look pretty good. Oddly enough spices seem to come up on this list frequently, coriander, rosemary, cinnamen, etc.

Other items in the list:
Soy Protien Isolate
Cauliflower
Cactus(!?)

If you go to the Low Carb Kitchen Forum you can do a search for recipies that use these items.
Hope this is some help!
Archie