NASM offers live workshops and online. I took the online because I couldn't afford to wait for the next scheduled live one.
The test is two part. First, a 100-question multiple choice exam on general biology, physiology, nutrition and then also the specifics of NASM-style training. Second, a case study. I had to design workouts including all of the following: warmup/cooldown, balance, core, reactive, and strength work. This was done for a randomly chosen case study. I had to do three workouts: one to be performed immediately (client is beginner w/postural issues), one projected 2 months in the future (different phase of training, assume postural problems are fixed), and one 2 months after that (a new phase).
It's probably not as popular as NCSA or ACSM but with those who do know it it's just as highly reputed if not moreso.