I would love to see some Arcana Evolved classes converted to 4E.
Concepts that come to mind:
- Runethane. The major concept of his class is that it uses runes that can be applied to surfaces and objects. He is probably a leader with a strong controller aspect. I am alreadying working on that. The Runethane is a little like the ARtificer, but instead of using constructs he uses runes.
- Greenbond. Flavor is a little of a Druid or Spirit Shaman, and the class has a strong focus on healing. Could just be a Spirit Shaman, of course, but the Spirit Companion itself doesn't fit. Most likely a Leader with a Defender or Controller bend.
- Akashic. Gains access to the collective memory of the world, can read minds (by reading the most recent memories), just knows a lot of stuff. In combat, he can use the memories of the past to gain combat bonuses for himself (but maybe also for others in 4E?). Seems mostly like a Leader with weak secondary roles.
- Mage Blade. Like the swordmage, but as a Striker.
One idea that is entirely based on "mechanical needs", not on anything based on fluff or style: A class that uses constitution for attacks. The Warlock is at the moment the only one that does that.
But, maybe there is some flavor to be had: It's a character using the Elemental power source, channeling elemental energies through his body. It's not about intelligence, smarts or insights, it's all about building up powerful energies without being destroyed by them. Maybe take some hinds of the Malediction Invoker (self-inflicted pain).
Of course, you might run into the same problems with this class as you did with the Assassin - WotC is probably working on something like that, too.