Warning: The majority of the information below will probably bore the hell out of anyone that isn't interested in game design. Read at your own risk! If you aren't interested skip to the end to look at the pretty pictures.
For the last while I have been primary working on game design which in my opinion is the most important part of making a game. The programming is mostly completed, but before I go any further with making the screens look good of finishing off the game editor I need to complete the game design. Getting the game engine working and throwing a couple test monsters, items and skills in it proves that the overall concept of the works. The hard part is making that concept fun. I read a great book called "Game Design: A Book of Lens" last year. It provided am in-depth look at why we enjoy playing games and what makes a game good. Now come the hard part of planning out the stats on all the monsters, equipment, items and skills.
When making complicated game like a RPG with lots of stats, monsters, skills and equipment everything is interconnected. You need you make sure the HP of the player is equivalent to the damage the monsters are doing and the damage the player can do is equivalent to HP of the monsters. That the player has the skills and items needed to counter the monsters abilities at that level.
Everything needs a starting point, so I chose the players base HP per level. To work off the players HP I need to have an idea what level they will be at each depth of the dungeon. I created a spreadsheet to that worked out roughly how many monsters I expect the player to kill on each level. Once I had the level of the player at each depth it was easy to work out the HP they would have at that depth. From there I could start creating monsters by selecting an average depth for them, their average damage (based on how many HP the player would have at that level) and then assigning their HP. Right now I have 80 monsters in my list with all their information filled out (currently I have the art work done for 23 of them). Also how that I know the monster damage and the players HP allowed me to create a list of all of the armor that will be in the game, which is currently at 82 items. I have 6 spread sheets on the go with different information and charts in all of them to help me plan the flow of the game. I also have a Game Design Doc that has all of the formulas and the reasoning behind everything in the game.
Here is a sample monster. The "Mimic Chest":
I have also created the Grim Reaper for the Wheel of Fate screen (which still needs a bit of work).