Taking on an ab challenge

One of my friends from high school posted a challenge on Facebook on Monday, which lasted until today. The event was called: 1000 Sit-ups/Crunches Week.
I took on the challenge and completed it this morning with the last 75 (but actually did 80–had to get it even for the obliques) for a total of 1,005 for the week.
I takes me about 5 minutes to do 100 crunches, all styles. So I figured I could take on the challenge and complete it in the time allotted.
On Saturdays I take a 30 minutes abs class. I didn’t attend yesterday as we had a friend in town and we headed up to Napa for lunch and wine tasting. I got to the gym early yesterday and did 500 abs/crunch work in about 20 minutes before spin class.
While in yoga the other night Vickie asked me about this challenge I was in. She told me plank pose is the best core work, which makes sense to me.
I found this article on About.com, which links up to a variety of ab work. I have practiced all these.
This article, 6 Pack of Myths on Ab Training, talks about some ab training myths. The one I find interesting the most interesting: High repetitions are required to make gains.
When doing ab work in yoga this comes up quite often. The various instructors remind us that slow and few ab exercises are just as effective. Elbow to knee is killer. Oh man, we only do like 10 total and I am dying! This Yoga Journal article is great: Describes the pose and provides a picture. If you want to work your abs try some of the poses described.