Fable II

The first part of this solution is a warning. This solution is missable even though it is not marked as such on TA. There are keys in Bowerstone Market and in the hobbe cave that you must dig up. Depending on your choices at the end, you may not be able to dig any more. You could still get this virally, but if you want to do this yourself then you should heed the rest of this guide.
To avoid this you can do several things. First, when you start the hero of skill quest, you will be sent to wraith marsh. This will open a new cave and you will now have access to every area that has keys. You may want to complete the key gathering before returning to the hero of skill. This way you will not have to worry about what you choose in the end. At the very least you should gather all of the keys in Bowerstone Market and Rookridge before you return from that quest.

If you are interested in completing more sub quests after the final mission, then when you have to make a choice at the end of the game, choose the needs of the few for your final choice. This will allow you to still dig.

There are several keys in out of the way areas that are accessed during certain quests. You should do the quests: Hobbe Squatters, Love Hurts, Treasure Island of Doom, and Rescuing Charlie. Each of these opens new areas that you need to access in order to find the keys.

You will also need to buy the cemetery mansion and if you saved Giles farm you will need to buy the farm. Buying these gives you keys to access Shellby crypt and Farm Cellar, each of which have keys. Also, the cemetery mansion has a key that you cannot get to unless you own the building.