Podcasts are gaining in popularity on the web and almost everyday someone is launching a new podcast. Users are flocking to listening interesting podcasts on various new topics, it's easier to catch up on new trends without losing focus on their day-to-day jobs. This .net TLD with pod prefix and word 'castle' is easy to remember and could serve this niche very well.
Great news! Domain PodCastle.net has been registered in the past and previous domain owner(s) may have forgot to renew or dropped it.