All of these methods are at best arbitrary and at worst highly judgment dependent. They can also cause consistency problems; if the DM makes an off-the-cuff ruling on DC every time, then eventually some inconsistent results will occur ("Last time we tried to make that leap, it was DC 15, why is it DC 20 this time?"). If the game includes a long table of modifiers or preset DCs then it becomes impossible to memorize and quite hurky.
I was brainstorming some possible solutions and an idea jumped into my nugget while driving to work. Why not create an "economy" around skill checks? Instead of a command-and-control centralized planning system where the DM sets all "costs" (DCs), why not a "free market" model where the players can barter on what the true cost of an action is? One model for that is a gambling model. For example, in a round of poker, each player estimates how much their hand is worth in relation to the pot.
One problem with this model is that the players may generally have an incentive to gang up against the DM; all members of the party probably want to succeed and the adversarial DM wants them to fail. So the system must either strengthen the hand/influence of the DM (i.e., different amounts of pull or influence), impose transaction costs, or both.
Here's an example of how such a system could work.
* A player wants to leap across a chasm.
* The DM decides whether its worth opposing or not. If the DM decides there should be a risk of failure or an expenditure of resources, then he will oppose it. If he decides there is not, then he just allows the action to succeed, no check required. This step should reduce frivolous checks.
* If the DM decides its worth opposing, he "antes up." He puts some resource into the pot that everyone at the table values. For example, this could be action points (usable by NPCs if in the hands of the DM or by the PCs in the hands of the players), "plot points" (again, usable by both sides), healing surges, gold coins, whatever.
* The player then decides if they are willing to ante up to match the DM's wager. If not, then they do not succeed (nothing ventured, nothing gained). If they meet the ante, then the gods rake the pot and then the mini-game begins.
Raking the Pot: The "Gods" or "Fate" should take a cut from the pot. These chips should effectively leave the game (although groups could allow them to re-enter the game in certain circumstances, such as the common house rule in monopoly allowing people who land on "Free Parking" to take the "kitty" of previously paid fines). This incurs a transaction cost and discourages frivolous skill competitions which waste everyone's time.
One could use a variety of models for the minigame -- poker, dice games, etc. Let's go with a simple variation on "klondike," a poker like dice game.
*Throw a total of five dice. In traditional klondike, the order of dice is 1 (highest), 6, 5, 4, 3, 2 (worst).
*Score "hands" of dice to determine the winner. From best to worst:
* Full House (Three-of-a-kind and a pair)
* Two pairs
* One pair
* For a quick and simple skill check, you could just play a quick version of Klondike as above. The player and the DM roll 5 dice and see who the winner is. As a wrinkle, highly skilled characters could roll more dice and take their favorite 5, or reroll some dice.
The winner gets to take the pot, but either way the action succeeds. Note that its up to the DM to set the risk of the action by anteing up at the start.
* For an important skill check, the process should be more involved. Either stud poker (such as 7-card stuck) or community card (Texas Hold 'Em style) would make good models. These include multiple rounds of betting and allows for more strategy. Here's a procedure using a variant on Omaha Hold 'Em (similar to Texas Hold 'em) rules.
- Ante up
- Each player rolls 2 dice as their "hole" cards. If skilled, roll 3. If highly skilled, roll 4. These should be kept secret if possible.
- Set up community pot by rolling three dice ("the flop")... Anyone can use these dice; they are shared.
- Add one more die to the community pot ("the turn")
- Add a final fifth die to the community pot ("the river")
- Rake the pot
- Score hands and determine winner. Players must use exactly TWO dice from their private "hole" dice and exactly THREE dice from the public community dice. The winner gets the pot. The action always succeeds; we are just determining how much the cost is.
Here's a wrinkle: Say additional players want to help with the skill check. They should be allowed to ante in and play the mini-game as normal. However, for each additional player, the DM gets to add one die to their private hole. This, plus the rake of the pot, should limit unlikely to succeed "aid another" attempts. This also creates competitive motivations within the party, as its a winner-take-all system.
I'm sure this needs some refining, but I think it could be quite interesting.