Well, minecraft is coded so you are only able to spawn on a few blocks (grass, dirt, leaves and sand) so I don`t think its possible. Maybe there is a seed that puts you next to or above it but no instant death.
In 1.1 there was a seed that could do exactly this, that's what I'm looking for. Also, on the seed "Novak" or something similar you spawn in the middle of the ocean, therefore proving you can spawn on something different than what you mentioned.
I've been an Administrator on this server for many months now and I have to say I had never been part of such a professional and well-managed community before this one. The way in which the server is run is extremely smooth and I'm sure you'll enjoy the experience as a player as much as I have as a staff member.
I realise this may look biased as I'm a staff member, but this is my honest opinion.
Similarly to Kyuhl, my opinion may look biased, but here goes.
Our community has been awesome since day 1 back in September of 2012. We've worked tirelessly to provide an awesome experience for our playerbase and I hope we can continue to do that indefinitely. I can safely say you'll enjoy playing here whether you're currently into PvP or not.