Then, through the miracle of Google searching, I stumbled onto the best ab exercise resource to date. The American Council on Exercise commissioned a study performed at a biomechanics lab in San Diego to determine the most effective abdominal exercises, including machines and other aids. The results are surprising. Here is the link.
Yesterday I opted for the bicycle, captain's chair, vertical leg crunch and hover (aka plank) in a cycle of 3 sets of 10 of each exercise. I am happy to report that not only were they effective (hello, familiar burning sensation in my muscles!) but I am pleasantly just a tiny bit sore today -- the sign of a good workout. Count me among those who is happy to say farewell to the antiquated crunch :)