Couple of rules for this game -- slightly modified from theoob's fantastic Pitboss rules:
1. Missing Turns -- Anyone who misses 3 consecutive turns (which would entail not taking a turn for at least 72 hours) without notifying me that they are going to be away will be replaced by an AI player immediately and then replaced by a human player as soon as is convenient. Once you have been replaced by a human you will not be able to take your game back.
To notify me of planned absences, you should either send me a PM or an email, and you should also rename yourself in the game to 'on holiday' or something like that, in case I miss your email (it's happened in the past). Note that I must have heard from you in some way, it won't be enough to say that you tried, if you rename yourself in the game there's no plausible way I can miss it.
2. Consecutive Turns -- It is possible to take a 'double turn' in the game by being the last to finish for one turn and then the first to finish the one after that. This has a positive effect because it speeds the game up, but the downside is that it can be exploited for military advantage by moving twice before your opponent has a chance to react.
So to keep the upside of double turns while eliminating (or at least minimizing) the downside, the rule is that if you are at war with another player (or are about to go to war with them, eg. sneak attacks) then you mustn't take two turns before they've had a chance to take one, or in other words you cannot go after them in one turn and before them in the next.
You can use the civstats log page for the game, or the RSS feeds from the same page, to tell if the other player has taken their turn (ask me about this if you don't know what I'm talking about).
A player must give his opponant as much time as needed to avoid a double move against him, playing first in the turn only when failure to do so would result in the turn being missed. In the case of sneak attacks or the outbreak of war he should alert his opponant via PM or email.
3. AI's -- When a human player drops out and I'm looking for a replacement, I will have the AI take over temporarily. While the AI is in charge, you may not make any deals with it other than cease fire arrangements (which may or may not include reparations). This is because the AI may agree to silly deals which the human replacement would have to maintain for the minimum of 10 turns before they can cancel it.
4. No War in First 10 Turns -- To be more specific: no declarations of war are allowed in the first 10 turns of the game. Otherwise you just know some poor (perhaps inexperienced) sap is going to be gone before they have a chance to do anything. You may however make preparations for a rush in this time, as long as it doesn't necessitate a declaration of war in the first 10 turns.