I play on eurocraft, but am still pretty much a solitary soul. I have also looked at realmcraft and massive craft. Other than that I use the A Higher Place site for CPD and have a bukkit server on my laptop to get used to building a learning type server, very lazy on configuring plugins for it, especially permissions.
There are no stupid questions and mistakes are opportunities to learn in disguise
I have a server I run for me and my family that I use as a playground (survival). I also play on Empire.us, which is a good place to see Minecraft players of all kinds. It's not an education server at all.
I know there are some servers that do roleplay (Hunger Games, prison, etc)...never tried one of those.
I've been into Joykay's server on a tour, which was fabulous! However, since it's K-12, it was a temporary thing.
I mostly just play with friends on their servers - I've never been one to just jump into a multiplayer world with strangers. When I play with friends, it's easier to define rules and borders we can all agree on.
Here's to all the educated people who don't hate games! -