Google-fu turned up PhilosophyForums.com. It seems like a decent first-order approximation of where we could send people looking to post on philosophy less analytically/technically than is typical here.

Does anyone know a better option? I only found that site just now...

ETA: Further searching for specifically rationality-oriented sites that aren't subtitled something-about-atheism isn't turning up much; and we might want to keep the attention of theists at least long enough to inspire some thought!

Perhaps RobinZ's suggestion to use the proposed open thread/discussion board/forum thing is the best.