We have various house rules. These are not fixed, we are changing them all the time.
We may instill a rule so that there is a time limit between the start of your turn and the time you first throw the dice, to stop a slow deal from blocking the game. This is known as the "one minute rule" for obvious reasons.
Until you have passed Go for the first time, landing on property does not initiate a sale or an auction.
Taxes (luxury, the 10%/$200 thing, and anything paid due to chance or community cards) go to a pot held under the Free Parking corner. At the start of the game this is seeded with $100. A player that lands directly on Free Parking collects the pot.
The pot is reseeded with $100 each time someone collects.
If you go to jail, you not may immediately pay bail or use a get out of jail free card, you must wait the next turn to do so.
On each turn spent in jail, you may either try to roll a double, or pay bail. If you try for a double and succeed, you then immediately play again (as if you had rolled a double and thus landed in just visiting). If you pay bail then you are moved to just visiting. You may not do both.
On the third round in jail, if you fail to throw dice then you must pay a release fine.
Bail is $50 or one "get out of jail free", as is the release fine.
You may not owe a player money at any time. You may of course give money to another player at any time, so long as there is no agreement that says they must ever pay you back.
We usually allow any deal to go through (except loans).
Per the rules, only tangible deals with assets owned at the time of the deal are allowed.
Every deal (or alternatively just deals that involve more than immediate exchanges of tangible assets) must be agreed by a majority of at least 50% of the players (whether bankrupt or not) not involved in the deal (i.e. regulatory approval).
All deals are open, no secrets may be kept.
You may only purchase properties at the start of your turn before throwing the dice.
You may sell properties at any time.
All the purchasing and selling of houses and hotels in ones turn is considered a single atomic operation that starts at the beginning of the turn and ends at the throwing of the dice (or at the paying of the jail fee if appropriate).
We play that you can only start buying properties after you have passed "Go" for the first time.
The official rules are usually used.
You may sell a property back to the bank for the face value price (except on the turn during which you bought it from the bank). The bank will not auction properties that are returned to it if someone goes bankrupt; they are merely put back on the market.
The moment dice are thrown by the next player (not necessarily for the next move, e.g. if the player had a double) any pending transactions that have not been initiated (e.g., collecting rent, getting $200 for passing go) are forfeited.
If a player is bankrupted, all his assets are sent to the bank, which then pays out the debt in full. (For example, if Hixie lands on Pavlov's ghetto hotel (rent $250) and he only owns one railroad (mortgage value $100) plus a $50 bill, then he returns the railroad and the $50 to the bank, which then gives Pavlov $250).
The official rules shall prevail!
See also: other monopoly rules, some hints and rules.