On further reflection, the second variant is not as sound as the first, but I'll post it anyway because I hinted at its' existence by saying "First up..."

Basically this variant tries to take the intense negotiation, simplified tactics, and the reliance on allies that the opening provides. In this variant powers are only allowed to build units by capturing the initial neutral centers. Capture of an already owned center does not give a build.

However, if all the home centers of one power are owned by another power at the same time, control of that power's units transfer to the invader. Play continues until one player owns four powers.

I once heard a reference to a varient that uses the classic map, but every single home supply center is it's own country. Thus you get 22 countries with one sc each. I suppose you could do one in which every sc gets its own player, but that would be a really grinding slow start, I would think...

Oh, that's the "Chaos" variant, and it's 34 players.

Hm, maybe that could be extended into a "Pandemonium" Variant, where every province is an SC, and every SC is owned by an individual player.

How about a map of the modern middle-east? Pakistan, Afgahnastan, Iran, Iraq,
Saudi Arabia, Israel, and Egypt? It would be kind of amusing. Maybe Padistan, Iran and Israel could each have a nuclear bomb or two--the ability to displace/destroy a unit anywhere on the board.
Any refinements to the idea? I'm sure some one has already thought of this...

I'd be interested in a "feudal" variant. You start with 22 players, on teams by country. Each one gets a vote for the king, who hands in orders for the power. Every time there's a build in your original SC, you get another vote.

If you want, you can hand in moves for any units built in your home SC. These moves supercede the king's orders for your units.

End of the game, the king gets half the points for a win; other players each get 1/4.

Chaos is available here: http://oli.rhoen.de/webdiplomacy/index.php and here http://goondip.com/index.php

Feudal would be interesting for the king at least...

could you change kingdom?
I'd like to see bolshevik, it is an 8 player variant on the normal map where the 8th player starts with no units, but at some point of their choosing takes over half a country (any country, again of their choice)

The bolshevik revolution usually hits the biggest country, and thus acts to balance games where one player is about to win a solo...